Okay, so these are my top 10 fave apps and tweaks you can get from Cydia.
10. Icon Renamer- Let's you rename any icon you want, pretty cool. ^-^
9. Barrel- This tweak gives your icons a 3D or a wierd affect when you scroll from side to side. Kinda hard to describe.
8. Infiniboard- Let's you have as many apps as you want on one board! I like this one.
7. AppStorelous- This was meant for Installous (#3), which adds a que or download button so that you can download any app for free faster. Useful.
6. Move2Unlock- Instead of Sliding to Unlock, you move your screen! This tweak makes unlocking the screen funner.
5. DisplayRecorder- Let's you record whatever you're doing on your screen. Ex. Gameplay, glitch, etc.
4. iProtect- Keep those creepers trying to creep threw your stuff away. You don't need a pass code for this, But you can put a pass code on any apps you want, Like Facebook, Twitter, etc.
3. Installous 5- Let's you download nearly any app for FREE! My favorite app.
2. BiteSMS- This is REALLY useful is you use The Messages app installed on all iOS 5 devices. Let's you reply to a message on Notification Center, Lockscreen, ANYWHERE!
1. iAP Cracker- Let's you get FREE In-App purchases! Really awesome, and cool.
I got all of these things for free, and you need these sources to download them.