Xeo UIUPDATED FOR 3.3.2compatible screen resolutions:
1920x12001680×1050 (haven't tested it, but I'm told it works)
1440x900 (haven't tested it, but I'm told it works)

Updated December 13, 2009
My goal is to have the most informative things at my disposal in the least amount of space, and still look good. All the essential things I look at while raiding (cooldowns, dots timers, my unit frame, target unit frame) are close to each other along with a large castbar for timing precision. I also like having 75% of the screen empty so I can see what's going on around me. This UI is not set up for levelling (no xp bar, but you could add one) or PVP. There are not any arena specific addons, and you'll only be able to see 25 out of the 40 people in AV. It's pretty much a solo/farming/raiding UI. Everything is tweaked and perfected around 10/25 man raiding.HD Video (Northrend Beasts (Heroic) 10) (3.2):

HD Video (Onyxia 10) (3.2):

HD Video (Mimiron 10) (3.1):

HD Video (XT-002 Deconstructor) (3.1):

HD Video (Emalon the Storm Watcher) (3.1):

HD Video (Malygos) (3.0):

HD Video (Loatheb) (3.0):

Screenshots (3.3):
Solo, out of combat:

Solo, in combat:

Multi-dotting example:

25 man raid, in combat:

Vehicle setup:

Bag/bank:

Bag/guild bank/hidden FuBar:

Let me know if you have any problems with it