Free until May 20th, which means you need to go download it now.
>Introducing DropKey. The hassle-free way to encrypt your files.

>We all send a lot of files. Whether it’s in Mail, with iChat, or even sharing them in Dropbox, files are still a huge part of our daily lives. Sadly, we haven’t had an easy way to make sure they can only be opened by the people they were intended for.

Now are you convinced?