My clones only use Jamba, mainly to save resources, as they're all run on 1 computer.

The main uses a lot of stuff;

Jamba <--obvious
XPerl <--easiest to set up, and shows each slave's cast bar
Carbonite <--just started using it, I like the tracking features (especially when trying to quickly level my druid right now)
Bagnon <--best bag mod out there, IMHO
DBM <--just the party and battleground modules
DoTimer <--nice little DoT/Cooldown mod
Elkano's Buff Bars
Chatter <--used to use Prat, but it was never updated on time
Bartender4 <--I like to hide any buttons I don't use, no screen clutter

If I had to pick 2, it would be Jamba and Bagnon I couldn't live without.