iOS (Jailbroken): If you use the stock Mail app on your iPhone, you know you don't have a lot of ways to attach files to emails. Attachments+ for Mail adds lots of options and control.
With Attachments+ for Mail you can save and open many different formats, and you can attach virtually any file on your iPhone. The handiest thing is that you do this all from the Mail app -- including browsing files, previewing files and compressing them. It's incredibly simple, but if you find yourself needing to email a random files located deep in the heart of your jailbroken iPhone's file system, Attachments+ for Mail is good to keep around.