If I were in your situation, I'd try to port a NetBSD userland utility (see
http://wiki.minix3.org/doku.php?id=developersguide:portingnetbsduserland for details).
Most of the easy ones are already done, but some candidates looking (reasonably) easy are most of the games and "less". Maybe also "lex" and "yacc" (anything that doesn't require a POSIX function or library not yet implemented).
Just check if the utility isn't already ported and the wiki wasn't updated.