I have found the following programs to be extremely useful for an Android phone.
Waves Tuner – very simple. Very accurate. I really like this one. Only $3.
Camera ZOOM FX – Decent camera app. Has stable shot feature which is very cool. Free and Paid version.
CamScanner – very decent photo to PDF app.
Easy Battery Saver – yep, saves your battery!
Mr. Number – block calls.
Themer – Makes your phone fun looking. Great themes, and easy to use!
SOL Calendar – Very nice calendar