In no particular order:
RealCalc – Calculator app
Titanium Backup – System backups (apps and data)
VLC – media player
SyncMate – sync contacts and such with my Mac
Voice – Google Voice
Root Explorer – File Manager
AVG or Avast – Anti-virus/firewall/security
aCar – mileage and expense tracker cause I’m a data nerd
Vysor – Lets Mac display android screen for presentations and such
Pandora – Gotta have my tunes!