Theeeeere he is again, TukUI!
http://tukui.org/screenshots.phpThese days, TukUI is even published on Curse, thus also available trough the Curse Client, no more digging trough the bit-unfriendly TukUI website!
No seriously, I'm using TukUI since the start of Cataclysm and I love it. IT adjusts automaticly to your screensize, offers high modifications and includes awesome stuff like a fully class-dependent configured Grid (If you run on your priest it will show diseases but not curses, for druid healers the other way around) tank/dps and healer layout that you choose once you log in for the first time on a toon, skins for other addons (installing recount, omen and DBM while also having installed TukUI will make Tukui auto-skin them to match TukUI)
I'm currently thinking about trying out ElvUI, the most famous modification of TukUI, which you can see in action in Blood Legion's Ultraxion HC kill just last week:
http://www.youtube.com/watch?v=5TVn4kYEvQMSo yea, TukUI delivers a complete package with a shitload of functions!
(if you decide to test it, don't forget about the /moveui command, it lets you move anything!)
Also, you can see my UI in action during our Raganaros kill, do mind that it is a bit cluttered thanks to the fact that I'm playing on a 17 inch 4:3 screen, any widescreen will solve that! (this was a previous version where skins for omen and recount weren't implemented yet)
http://www.youtube.com/watch?v=FnxAzxFUnJk