I also learned few simple trick that has kept my 8830 memory above 16 MB. Some of them have been listed here but some aren't, please forgive the redundancy:

Delete unused Languages
1. Go to Options >> Advanced Options >> Applications
2. Scroll to and highlight the unused languages
3. Press the menu key and select Delete
Note: When prompted to restart select No until all of the unused languages are deleted.
4. Once all languages are deleted, remove battery for 30 seconds and re-boot the device

Clear Cache and Cookies in Browser (This definitely helped a lot because I used to lose tons of memory everytime I surf the web for few minutes)
1. Go into the Browser application and press the menu key
2. Select Options >> Cache Operations
3. Select Clear History
4. You can also clear out Pushed Content and Cookie Cache from here

Clear Cache and Cookies
1. Scroll to and select the Browser or Media Net icon.
2. Press the Menu key.
3. Select Options.
4. Select Cache Operations.
5. Select Clear History.
6. Note: Clear History will no longer appear once it has been selected.
7. Hard Reset the BlackBerry.