My hunter raid UI:
https://netfiles.uiuc.edu/dloran2/www/june2008ui.jpg
My general design principle is to keep important stuff centered and at the bottom of the screen, which is where my eyes tend to hover on their own. Information that I don't often need during combat has been relegated to the top corner of the screen, and a large, wide area is open to see the game world. Omen (and my trap timer bar, which isn't in the SS) cover up part of guild chat, because I shouldn't be distracted by it while fighting anyway. The Demon-like line of debuff indicators above the target frame is simply a pitbull text.
I have a few clever UI tricks that I'm proud of. I don't need to see my name or my class on the player frame, so i've replaced them with a display of my AP, Crit, and Shot speed (this is PowerDisplay, with the appearance modified via lua), and an indicator of how many mp5 Aspect of the Viper would give if I turned it on (this is a clever dogtag). My main elk buff bars are long buffs (> 10 mins) at the top, and separate lists for timeless buffs and <10 min buffs plus all debuffs below the player frame. On the right side, target debuffs that are important to me are shown separately. Even as a hunter, I use Click2Cast along with main-tank and raid frames for Misdirection and Scorpid Sting (which are bound to the same button, and selected based on the hostility of the target).
The one piece of the UI that I'm not terribly happy with is the button bank below the target frame. Those are mostly cooldown abilities and items, so having buttons serves as both a way to activate them and monitor the cooldowns. However, just about everything else in the UI is bars, which I like better than icons and text. Anyone have a good way to track cooldowns as bars and a space-saving way to activate them?
All the standard ace players: Pitbull, Grid, Quartz, Prat, eePanels, Bartender, ElkBuffBars (this is probably my favorite mod in the world - I have 8 buff groups), Omen, Chinchilla, FuBar, Parrot, CowTip (very customized, I can post screenshots and the dogtags if anyone cares).
Fubar modules (Yay, zero minimap buttons!):
Bottom left bar: MoneyFu, MailFu, GuildFu, FriendsFu, QuestsFu
Bottom right bar: oRA2, BigBrother, CCBreaker, Outfitter, AmmoFu, DurabilityFu, BagFu
Above minimap: PerformanceFu
Below minimap: TrackerFu, BattlegroundFu, Addon Prefs, BugSack, ClockFu