Ok, I've spend the whole evening writing that thing, so please take a look - there's some really nice mods listed here.
I've always been a freak for addons, it's the same in Firefox, and it's the same in WoW. So, here's a defnitly too long list of the mods I'm using, with some screenshots and my comments. Definitly too much text, oh well.
Firstly, is my fav site for addons. Go take a look.
Screenie of my general UI (all printscreens of 1280/1024, non-resized 'coz I'm lazy):
http://irian.nd.e-wro.pl/wow/UI.jpgMinimalistic and functional - just the way I like. And now, the way I achieved it:
- Those two small bars on top and bottom - though, you can place them both together, or on sides if you want. I used TitanBar before, but I switched to Fu and I really like it better - it has all the features of Titan and many more possibilities. Almost all Ace-based addons have a FuBar icon included, it helps keeping everything clean. Most of the modules are small, fully configurable and handy. You can choose to show text or icon for each of them, place it according to your fancy and so on. You can also export your profile settings to your other charas. Lovely. <3
My
, as shown on the screen from upper left:
LocationFu - since I have the location plate on minimap disabled, it takes care of that small thing for me. Also shows on mouse over: instances in the zone, recommended zones and instances... And coordinates, if you want them. I didn't.
GarbageFu - might look humble, but it's THE addon I've been praying for many times before. Allows you to one-click drop the cheapest item(s) from your inventory, also one-click vendor grey loot and generally takes care of your bag garbage. Fully configurable, including exceptions lists. It also shows your bag space, but I've disabled that options, since I already have BagFu (which looks better, that why I've left it.

)
AuldLangSyneFu - I don't remember if I downloaded it with , or later, but it does require the ALS to work. Nice friends/guildies manager.
RestFu - shows rested ratio of all your charas.
WIM - WoW Instant Messenger. It's not really a FuBar addon, but it does embed in FB, for which I'm quite gratefull, as my minimap buttons became quite cluttered before. Sorts and manages whispers, remembers previous conversations with people, even after game restart.
EmoteFu - just for the fun of it XD You never knew WoW has this many emotes available.
ExitFu - small and lovely, one-click logout/exit game.
Lower bar:
SkillsPlusFu - manages all your tradeskills in one tooltip, also takes care of cooldown skills (has a build-in tracker).
QuestsFu - quest log on fubar. I'd get rid of it, since I have a really brilliant quests addon, but I like the tracker it has. Small, yet clear - you can see it in place of the regular quest tracker.
LogFu - the 'just in case' Addon of Anti-Drama - logs the chats and battle-logs for me. Like I said - just in case.
PerformanceFu - yet another 'I don't have the regular Blizzard-build-in UI, so I got an addon for this'.

Takes care of latency, framerate and so on, as Bongos made this bar go poof.
ExperienceFu - Shows exp per session/hour/level/total or any variation. Also counts time to next level using current exp rate.
DurabilityFu - durability of the items you wear and have in bags.
BagFu - simply shows bagspace. Handy.
MoneyFu - my gold on hand.
I also have
ClockFu - Um, a clock? I don't have it on the printscreen, as I only use it on charas with Group Calendar disabled. No need for two clocks, doh.
Now for the bars... Wait, where are they? Yeah, I didn't really like what Blizzard calls fully-customizable (yeah right) bars, so I got me the Bongos addon. And all the bars went poof! Took me a whole day of cussing and throwing heavy things at everything that came near (mostly my cats and, later that day, Raven

), but I must say I'm quite proud of the result.
will really destroy all the precious, long-thought key bindings and buttons placement you had. And then it'll make it better. You can move your bars, resize them, make transparent if you want, and bind any key to anything with just one click. You'll love it once you get through configuring the damn thing.
As you can see, I have my most used skills near my portrait, so I can see their cooldown easily. The big button on the right is my 'panic button', not really working at shaman, but my pally has her 'lay on hands' there and it's really nice for last resort. Of course I have it key-bound, but sometimes when you panic it's just easier to point and click.

I should probably get rid of small shortcut icons (the character, skills and so on) on lower right, but I'm too used to them... And if I screw the binding one day, it'll be nice to have a way to get it back without disabling the whole addon (well, actually I already did that once, bound something under 'esc' key and if not for the button I could click, I'd have to disable the addon. Bah). Quite-often used totems are also bound, and threw down there, while the smallest bar consists of rarely used skills and some macros.
Ah, I didn't check it with my druid yet, but a friend of mine says not to use this addon with a drood - the bars wouldn't work for him when changing forms. I have yet to try this.
But! Bongos itself wouldn't make my buttons so pretty. That's where I used
. Just a skin for Bongos and several other UI mods, allows to choose from various button styles, round, square, even hexagon. Just to pretty it up a bit.

For my totems... Ah, yet another addon.

Meet
, one of many Necrosis children - there's a spherical addon like that for many classes (I believe Hari has one for Warlock). Center button is configurable, with left and right click, also can show one stat (mana, hp, whatever) as blue circle and another as percents in the middle. There were more buttons around the circle, but I won't use half of them, so I disabled them. The ones I use are weapons buff, a self-configurated button for all the elements totems (I really love this feature to bits. You have no idea how frustrating can a totem search on cluttered bar be. There's like a thousand of those lil' demons. X_X) - the most/recently used one is shown on the button and can be cast by left-click, the previously casted is accesible by middle-click and all the list shows on right-click. It also includes the totem timer. Makes my life easier. <3
Now, an important addon that isn't visible on the screen:
- allows to see full map, add notes, set waypoints, check instances and their bosses. I used MetaMap before, but it was most of time out of date, so switched and there's not really much difference.
There's also
, which is a must-have for everyone. Saves gathering skills info from all your charas and adds it to map, so you won't have to learn all the herbs/ores position, you can just check anytime you want.
And now, for something completely different - I present you THE quest log addon of the win.
while not really light, incorporated WoWHead.com quest database to your quest log. Just take a look:
http://irian.nd.e-wro.pl/wow/lightheaded.jpg All you need to know. Plus users comments. And if you click the coordinates given, you'll get them as a waypoint on your map. Alttabing never more! (btw, the 'Quest nr XYZ' you can see on screen should be a regular quest name, only I didn't wait for it to load.)
Another usefull addon is
- we use it in our guild for events coordination. Creates a manager with several access levels, allowing to post, accept and participate in events. Also gets you a clock on your minimap button.

- better looking alternative to KTM. Still beta, but works fine for me.
Ok, that would be the most important addons I use. Now, for some smaller mods in alphabetic order:
- allows me to group guildies by alts, also colors them by class. Nice if everyone in your guild hase ten thousand alts there X_X.
http://irian.nd.e-wro.pl/wow/betterguild.jpg - while it's a hudge mod, I discarded most of it and I'm using only several small features, which are MailMod - allows me to easily send multiple items to the same person, handy with banking; PartyBuffs improves display of party buffs, doh.
- aaaah, it's good. Allows you to simplify several UI elements (chat, minimap), as well as adds some functionnality - auto decline duels is the WIN for me. Never more stupid duel spam. Yay.
http://irian.nd.e-wro.pl/wow/minimalist.jpg - frustrated about those dumb default windows you'd just love to move out of the way? Well, now you can. This addon makes most of UI panels moveable.
- install it, and log in to each of your charas, then check your banks. This mod will remember all the items on all your charas - wonder if you have somewhere that leather you need ATM? You can check now.
http://irian.nd.e-wro.pl/wow/possrest.jpg - changes all those mysterious numbers in your ratings to percents. Also shows how this percentage will change with new armor/weapon.
- adds another bar under hp/mana, with exp. Nice design, I only wish it showed rested as well.
Urgh, there's a LOT of that. Well, I'm an addict and I really like those small functionality mods. I'm also using the Auctioneer and Mendeleev, but Owa already posted those.
Also, when you have such a big number of addons, keeping them up to date can be quite a challenge. But no worries, helpfull people out there thought about it, too, and every Ace-based addon (most of mine mods are Ace-based, thankfully) can be updated using program. It does download betas, though, even if it never really caused any problems to me. Your choice, really.
Now, go and have fun choosing addons you like and find useful. <3