Here's a video of my feral UI in action.
I have my grid frame set to hold 25 mans, but 40 mans (like the AV bg) will only cover up skada (DPS meter), which I have turned off for bgs anyway.
The spaces to the left and right of the unit frames are buff/debuff containers. They may look large, but raids get a lot of buffs and it's my personal pref to see what I have on me.
As you can see, I do like using power auras to track procs, DoTs, and cooldowns. the empty space between the player and target frames is dedicated for my power auras. I like seeing timers on my abilities so I can bank energy or burn it depending on what's coming up next.
Here's a breakdown of what's what, starting from the left bin. I have savage defense (green shield) and berserk (red face) monitored in large icons. The feral charges are next. Activating cat or bear charge will put both charges on cooldown, but bear is on a 15sec cd and cat is on 30. If you use bear when cat is off cd, both have a 15sec cd. Tracking these gap-closers in PvP, and sometimes PvE, is a must. Cat (yellow arrow) is on top and bear (red arrow) is on bottom. Skull bash (blue skull) is to the top right, and below it is an indicator for thorns (I rarely use thorns and I should, so I tried this out and it helps remind me keep it up on a tank or healer in bgs).
In the center bin, I have prowl (purple swirl). The swirl will only show up if I am able use prowl (ie must be in cat form out of combat), but I have a timer tracking the actual cooldown of the spell so I know when I can shift into cat form or pop shadowmeld and use it. Next I track stampede (red icon). Because it's a free ravage from using feral charge, I like to have it on timer and use it at around 80% health on my target after I've burned through some of my energy; it's very important not to loose this burst potential, especially in PvP. To the right of this, I have timers for berserk and survival instincts. While I already have auras tracking their cooldowns, I find it very helpful to know how long each buff is active and plan energy usage or bear form accordingly. I have my cd and buff duration for tiger's fury (green paw) to the top right of the bin. If possible, getting a rip off while the TF buff is active increases DPS, so tracking the duration of TF becomes necessary. Below the TF aura is a icon for faerie fire (purple faerie) with stacks.
In the far right bin, I have my target debuffs tracked with timers. Working outward in, I have savage roar (bottom blue dot), rake (yellow), mangle (orange) and rip (red), all of which are tracked with timers to their left. The timers help me gauge my energy usage to keep all my debuffs/buffs up. It makes an otherwise rather complicated dps priority system very manageable.
Above the far right bin is an power/combo point tracker. I have energy/rage displayed on my unit frame, but it's on the other side of my screen. Looking back and forth between it, my buff tracker, and my target frame makes for a lot of moving about. I decided to track energy/rage inside my combo points. The yellow dots are energy (red for rage) and the colored circles around them are combo points. When I reach 5 combo points, a green box surrounds the tracker and makes a ding noise. If I'm chasing something down trying to finish it off and stop paying close attention to the tracker, the ding will let me know I can throw in a finishing move. The tracker also shows lacerate applications and a wear-off timer so I don't loose the stacks.
Finally, I have procs tracked around my character for clearcasting and predator's swiftness. It's nice to use the most energy intensive moves (like shred) when clearcasting procs, and it's always nice to throw an instant healing touch in PvP.
I've also made some space for misc things like pets, gearsets, tabards, and professions which aren't all that necessary but make my life a little easier. It's a preference point I suppose.
*Whew* so there you have it folks. Thanks for checking it out!
Notable Addons Used
Align: makes a grid on your screen for easy alignment of UI elements
Aura Frames: a buff/debuff display
Bartender4: customizable ability bars with fast key bindings and state config
Chinchilla: minimap manipulator
Grid2: party/raid frames
kgPanels: framework for UI (dark panels)
Mapster: moveable and resizable world map
Masque: custom look for BT4
MSBT: scrolling combat text
MoveAnything: allows for the moving and resizing of all UI elements
Party/Raid Hide: hides the default party/raid frames
Power Auras: highly customizable notification system
Prat 3.0: chat box manipulator
Quartz: custom cast bars
Shadowed Unit Frames: custom unit frames
Skada: DPS meter
SL Data Text: displays fps, latency, memory usage
Tidy Plates: custom name plates with enemy health and debuffs
Tip Tac: tooltip customizer