Cydia - An alternative app store for jailbroken devices.
Apple App Store - Install apps on your iDevice via the App Store.
JazzMyApp - Let JazzMyApp surprise you with amazing apps everyday. Try it out yourself.
Altstore - A home for apps that push the boundaries on iOS
Fnd - Browse Apple App Store and iTunes on the Web
iOS Haven - A listing of tweaked apps and games for iOS devices. Install directly from the browser.