Snippets are for useful idioms and tricks. I use Code Catacombs for code that I found fun and interesting but which I am unwilling to package and support. Code Catacombs also works for applications and PerlMonks specific stuff. Cool Uses For Perl seems to be for small little applications that people found cool.

The only one which I think would overlap CPAN much is Code Catacombs. And given a choice, I would prefer that people use CPAN...