BlackBerry client for Twitter, Facebook, and Foursquare.
This is my most favorite, most used application on my blackberry. I must have sucked up hard in my beta-app, because I didn't wait very long. I've seen it get better with each release. I send regular feedback, and get good responses back. I love that it integrates with Opera Mini (twitter), but it should offer the same thing for links in Facebook. It would be even more awesome if it pulled in my facebook friend groupings.