Addons I use, most of which are on wowace, unless otherwise stated:
Afflicted: Enemy spell/cooldown/cc timers.
BadBoy: Extremely minimal spam blocker AND reporter. Automatically reports gold spammers.
Bartender4: Action Bar mod.
BasicBuffs: Basic addon to move the blizzard buffs.
BasicChatMods: Basic optionless chat modules.
BasicComboPoints: Numeric, colored combo points.
BasicMinimap: A basic Ace3 minimap addon.
BigWigs: Boss Mod I'm a coding with Ammo and Rabbit, includes timers, bars, proximity module, and other cool plugins. There is also many 3rd party addons like BigWigs_VashjFFA for automatic FFA loot on Vashj, see 3rd Party Modules.
ButtonFacade: Bartender Button skinning.
ButtonFacade_Caith: Caith's skin.
ClosetGnome: Gear set sorting (Wardrobe) mod.
Combuctor: Ace3 inventory mod allowing viewing of yours bags in sections like 'quest' and 'reagent'.
fdFrames: UI Panel art I made.
LightQueue: Quick 'light' addon i made as an alternative to the StinkyQueue addon, used for simultaneous AV joining.
Links: Allows you to view multiple item links on the screen, but you can still close them all with Esc.
LittleWigs: Plugin for BigWigs, provides timers for 5 man instances.
Mapster: Ace3 map addon, shrinks the map scale and gives coordinates.
MikScrollingBattleText: The scrolling battle text.
OmniCC: Cooldown count for everything, available at wowinterface.com
oUF: Unit frames.
oUF_Funkeh: Unit frames layout.
Quartz: Casting bar with many many modules, including hot/dot bars, enemy castbar, latency bar & mirror bar.
SSPVP2: Battleground timers.
StatBlockCore: A core to make blocks of statistical information using modules. Modules are FPS, Latency, Ammo etc. and are named Broker_* and StatBlock_* (not to be mistaken withe the old version StatBlock(s)_* v1)
TickTock: Energy ticker.
Tinytip: A tiny minimalistic tooltip addon.