i was always to lazy to set up a CVS (or svn) repository on my own computer, also because then i don't have it elsewhere.

now i started to use google project hosting for projects which are not worth maybe to create a sourceforge project, for example. this is great. if you know you have all your past code in the revision history you can make changes without being worried how to roll them back if they don't work. an rcs is even recommendable if you only have one script.