The 99 problems list is a long tradition in software development. 
It started with prolog, passed through lisp, and appeared in many other contexts.
For a reasonable list of the problems with solutions in haskell see 
 http://www.haskell.org/haskellwiki/99_Haskell_exercises

This is just my attempt at it as I learn scala, feel free to fork the project or 
ask me (riffraff@github) and I'll be happy to add you as a collaborator.