I use the WhatsApp messenger to connect with my non-bb friends. It's like a BBM for everyone, either they have iOS, BB or Droid. Shazam is quite genious when you hear a song and don't know it's name. Shazam will find it for you.
Not to mention BlackBerry Protect! That should come pre-installed on every BB's. Keeps your data safe, and makes it possible to locate your BB if you've lost it.
I was gonna say BeBuzz too, customize your LED for contacts, text, e-mails, etc. And I love their new toast feature, you get a little preview of your text or emails. It's great.
I have most of the RIM apps, like BBM, Protect, News, Facebook, Twitter. I also like WeatherPlus as a weather app. It's free and the weather and conditions show up in the homescreen icon.