Tweaks in order:
1. Activator (FREE) - Assigns screen gestures and button press combinations to do a multitude of actions, from launching apps to controlling the iPad application.
2. Gridlock ($0.99) - Removes the requirement for the springboard grid to align and fill left-right and top-bottom without needing to use transparent icons.
3. AnyAttach ($1.99) - Cydia tweak that adds a paperclip to subject line of all emails, tapping allows your to add whatever your iDevice file you can find.
4. Graviboard ($2.99) - Makes you springboard icons bounce around
5. SBSettings (FREE) - Swipe the status bar to toggle your iPad settings like WiFi, BlueTooth and others. Cydia has many more add-on tweaks/apps as well.