Combat:
KissAssist for most combat situations
A custom macro (I did not originally create) our group has for raid content (still working on refining some of the classes, but the bard smashes our KA profiles and zerk smashes the CWTN plugin when doing multiboxing raids)
Downtime:
overseer.mac - I have it auto-run anytime my characters hit the guild lobby or guild halls, hands down one of my favorite macros
I use sellstuff, itemsort, parcel (for collects), and bazaar a lot between grinding/camping/hunting sessions.
explore for a few of the expansions that it handles well, including LDoN (which that alone justifies the purchase)
fragmentfarm for grinding the alaran tear
Tradeskills:
tsc for grinding to 54 TS + getting beginner trophy
combine for when the lag in PoK is unbearable (hasn't been a problem recently)
ts_scribe or whatever it's named now
tradesman for grinding AP, making individual items (such as needing an armor container), or force-learning a recipe that is 400+ skill points higher
Collectibles:
groundgrab (i haven't played with the plugins yet!)
collections, reward, shiny for grabbing out of houses and overseer frags
Some of my favorite plugins that you may not be familiar with:
relocate (primarily used with pok, anchor, gate, fellow, lobby, air) - sometimes I want to make a wiz/dru just to randomly TL people
autoaccept
autogroup