Here's an interesting distro:

[struggle4progress]

http://www.deftlinux.net/

It's supposedly an ubuntu-based forensic distro, which means it isn't supposed to alter your disks (no use of swap space &c) and provides tools for examining the disk. Perhaps naturally, there seems to be no immediate "install" option

Unfortunately, the manual is only available in Italian:

http://www.deftlinux.net/deft-manual/

This is frightening if you don't speak Italian and only look at the first 20% of the manual -- the rest is appendices, in English. You can use the distro in English

<on edit:> I had trouble running this from iso in virtualbox at first. Finally burned a disk and booted it on a different machine without trouble. But I couldn't boot the disk in vb, either. Finally realized -- for some reason I had nested paging extensions turned on in vb -- turned then off and the disk and iso both booted without problem