I just did sudoku-mr.lsp... Thanks for inspirations...
Cool stuff! :)
I think it would be fun to solve the first several problems with recursions (attempting yourself ofcourse, no hinting with the answers).
Sounds like you are just learning about recursion.
Nonetheless, at one time I was going to help translate some recursion lessons written by ElpanovEvgeniy (member here) written in Russian (not that I speak Russian though and he's damn near a genius so not sure what I was ever going to do) but you may want to see if that exists if you're at all interested in recursion. There was some good stuff in there (pick up more tips and whatnot).