Best ones for me are:
Google Mobile App (has Auto Complete, download from them)
Gmail
Google Maps (A must Have)
Where (Great to find things)
SmartGuard (blocks all unwanted calls you don't want)
Poynt (Another good search app)
Movies
The Weather Channel
Aces Traffic Pack Classic (good when your bored)
Bolt is pretty good yet Opera Mini is better.....
A good choice here
http://www.productusp.com/20-best-blackberry-apps.html
http://www.bbgeeks.com/blackberry-applications/top-free-blackberry-apps-884738/