If you've ever realized after you flashed a new ROM on your HTC EVO that you were missing an application or some data but didn't want have to back up your current setup, restore the old Nandroid, save the data, and revert back to your newer backup, then Nandroid Browser by Paradise Android could be the tool for you.
It's a new application for rooted phones that allows you to view and extract selected data from your Nandroid backups. You can easily open, save, Dropbox, or email apps/files/whatever content you choose to extract.
Nandroid Browser supports ClockworkMod backups and some compressed Nandroid formats. Unfortunately, TWRP compressed backups doesn't seem to be one of them.
Until we get a smarter recovery that allows the same functionality, this might be the best way to get at your backups without ever having to reboot your phone or restore an old backup.