Some of the Applications that I use:
aSQLiteManager alongwith ashell --> SQL database editor
Poweramp and the Unlocker --> Best Music Player
ABBYY BCR --> Business Card Reader
Flighttrack --> Excellent app when you fly frequently...gives all the updates on flight status, especially delays
Quickboot --> Good one touch boot and options
Swiftkey --> Best keyboard
Alarmdroid --> Awesome alarm app, flip for snooze, shake for snooze, etc. Very low on resources
Autostarts--> Useful when rooted. Can change applications for autostarts
Calengoo --> Best Calender app. Trust me, the best!
ColorDict --> Very good dictionary
Expense Manager --> A good expense recorder
FBReader --> A very good book reader with text to speech capabilities also. Try various plugins available too
Google Finance --> A good stock tracer with a good widget
Flip4scilence --> Flip for silence on phone calls
Go SMS Pro --> A great SMS appliction with auto sms, etc
Google Reader --> Good widget. Can be updated from PC
IM+ Pro --> A very good IM
K-9 Email --> A good Email client
Link2SD --> A good tweak when rooted..I find this better than rest for convert app to system, to user, uninstall system apps, etc
MX Player --> A good video player..Normally supports all formats
Notes Lite --> Best Notes application..the best I found
Notification Toogle --> Great and lightweight notification toogle with good available options
Tasker --> You need to check-out. Can do loads of things! Can also develop apps!
Picsaypro --> A good picture editor
RealCalc --> A very good calculator..the best I found
Shahpluscallerinfo --> States the operator. Quite reduntant after MNP though
Smarttools --> A fun to use app
Tapatalk --> Downloaded from a post on RIMweb itself
Merriam Webster Unabridged --> Excellent dictionary, downloaded from RIMWeb itself
Unit Convertor --> Unit Convertor app
Driodwall --> Need to be rooted, a firewall. A basic requirement that prevents unwanted applications from accessing internet. Useful for securing privacy.
Battery Full Notification --> A lightweight battery status notification tool. I use it when in charge to know that the charge is full. While using for first time, need to manually select notification tone.
ES File Explorer --> A good free file explorer with root options. Can also mount system as r/w