Yatca (free twitter app for blackberry)
This is not a new application but I did not see it posted here so I thought I would share it. This is a free Twitter app for your blackberry and it's puts a very low demand on your device. It does run continuously in the background but I have experienced no memory drain or battery loss with the application.
The thing I like most about the app is it puts your tweets and what not in your messages folder. It does give you the option to turn this off if you don't like it, but I personally love having all of my tweets in the same box with my messages.
You should all try it out!
Yatca OTA Installer for Blackberry
Storm users might have to disable compatibility mode in order for this to work. It works fine on my Storm, only after an OS install I must reboot the device in order for it to work properly. No big deal though, most people do this anyways.