Interface update! Since Cataclysm drastically changed a lot of the core mechanics to the paladin class, I've spent some time tweaking and reforging my UI, and I think I've finally gotten a setup that I'm comfortable with. It has the appropriate amount of information, without cluttering and creating tunnelvision fields, and I'm growing very comfortable with it. I will obviously have to tweak a bit further when we go into heroic raids and such, to fit in further information blocks (atm, my BigWigs text warnings are between my grid and my action bars, and that won't work in a 25-man scenario), but overall I've found the design I want to continue using.
Without further ado;
Combat text: I use MSBT for my scrolling combat log, simply because I feel this is the tidiest and most accurate option. Left side is incoming heals and damage, right side is outgoing, center below my feet are important notifications and center above my character are every buff, debuff, resource gain and status change on my character mid-combat. The three red "Spell is not ready yet" is a permanent feature on my UI... I simply can't seem to get rid of them.
Unit frames: For my core unit frames, I use Shadowed. Left side is me, tight side is my target, and the box above is my target's target. Shadowed also provides the buff- and debuff frames ate the top left of the target frame. For my own buffs and debuffs, I use Classtimer to keep track of everything important - they are the blue bars above my own unit frames and the target of target frame respectively. Grid centered between the Shadowed frames tracks my party status, such as mana, threat and health. I prefer this option over threatplates, as it's generally faster with my playstyle.
Actionbars: I use Bartender4, because it's simply the best. I also use ButtonFacade: Renaitre to add a more artistic look than the just the boring, regular squares. OmniCC tracks my cooldowns in a nice and handy way.
Corners: Left corner is Prat for chat. Beats Chatter hands down in every single aspect there is. Right corner is Recount for damage meters, Omen for threat, and TipTac for advanced target information on mouseover.
Not shown in the picture are Combuctor for bags and bank, and BigWigs for boss encounters. Apart from that, it's very much no addons to speak of - I like to keep my addon memory low, even if it means no sexy minimap and Blizzard's default aura- and buff trackers. I guess I'll survive.