This project is now maintained at GitHub, the version published here is deprecated
Zip Backup backups your projects into zip files automatically or manually, it uses 7z and fastzip and can achieve compression times up to x23 times faster than other conventional zipping applications.
It comes with a handy auto backup tool that automatically zips your project from time to time, preventing you from losing your work on eventual power outrages, Unity crashes, etc.
You can also backup manually by going to "Assets/Backup Now" menu, or clicking on "Backup Now" in the preferences window.
When the zipping ends, the extension logs how long it took and the size of the final file to the console.