I find that the sources included with Cydia are pretty decent.. rarely do I need to add additional sources to find what I'm looking for, however I do have these 2 sources added:
Welcome to Cydia.hackulo.us!
1. Lock Info w/ Weather and clock hide plugins
2. Pro Switcher + Backgrounder (They go together, because one works with the other)
3. AFC2Add - So I can SSH into my phone over USB instead of WiFi (More Secure, easier, faster)
4. Categories + CategoriesSB - Folders, but with the SB addon, they instantly load!
5. Infinidock - Keep my settings and Cydia/App Store apps off the SB, but easily accessed