iOS (Jailbroken): When you receive a text message on your iPhone, you always have to pop into the Messages app to reply. That's a little cumbersome if you just want to quickly reply to something. ImmediateSend allows you to reply to any text message from any screen quickly and easily.
ImmediateSend works in a similar fashion to alternative text messaging app biteSMS, but operates within Apple's built-in Messages app. When you receive a new message, you can immediately reply to it right from the screen you're on, or pop into the Messages app if you need the added context. ImmediateSend doesn't do much else, but it's a handy tweak that works well.