One app I find very well worth having is the Moonblink Tricorder app. It seems superficially like a silly toy app for Star Trek fans, but it is actually very useful.
Due to trademark issues, it's not available on Google Play, and generally has jumped from one obscure site to another. As far as I know, the most current version is available, at this time, at
Download Tricorder 5.12.3,Tricorder 5.12.3 5.12.3 Android download | 1mobile.com.
By the way, I would suggest that you seriously look into the possibility of upgrading your phone, possibly to a third-party ROM. Android 2.2.x is Froyo, Android 2.3.x is “Gingerbread”, and the Froyo/Gingerbread divide seems to be the cutoff point for many apps these days. I have a Motorola Triumph, which officially is Froyo-only, but I am running a third-party Gingerbread ROM on it.
It seems that a very good source of information for getting the most out of an Android device is the forums at
Android Forums. It has sections divided up by manufacturer, carrier, and specific device.