GPGMail is a plug-in for Apple's Mail, providing a front-end to gpg for some operations. It allows you to read/write encrypted messages, as well as electronically signed messages.
Snapz Pro X allows you to effortlessly record anything on your screen, saving it as a QuickTime movie or screenshot that can be emailed, put up on the web, or passed around however you want.
Ever wanted to hibernate on your Mac? Put it to sleep without using any power? DeepSleep will do the job for you. DeepSleep will put your Mac to sleep without using any power and wake up just like you left it.