Heh... when I saw the subject line, I thought maybe some recent distro had done something to really piss you off (like say Ubuntu's Unity desktop, or GNOME 3), causing you to swear off of using desktop Linux entirely!
Yes, these lightweight special-purpose Linux distros can be quite handy. I haven't used RIP Linux, but I've used Knoppix for similar things before.
I've also used Ubuntu CDs (their install CDs double as live CDs) to test systems and clone hard drives. When we upgraded the RAID array in the software group's Linux server at work, I used an Ubuntu live CD and a spare workstation to build the new array and rsync
the contents of the old array (which was still live during the initial rsync pass) to it over the network. Then, after hours (when nobody else was using the server) we did a final rsync pass (which completed very quickly since only the changes needed to be copied) to catch any files that had changed, and swapped the new drives in to the server. Quite painless!