Yes. Programming for *very* old Macintoshes can be interesting because they are nice-looking systems and because the little memory and rare documentation make it a challenge.

Example of a program presumed to work on Systems 1 to 9 (and "Classic") but only tested on System 6, Mac OS 9, and "Classic" :
http://sites.google.com/site/bl0ckeduserssoftware/past-projects
(see "pfacto")

It's not much, but it's better than nothing I guess