This is a list of programming challenges :

• 99 Problems in Prolog, Haskell, Lisp, OCaml is a set of basic programming exercises, tailored to Prolog.Users of strictly typed programming languages, will find it tedious to implement the tree-like datastructures.
• Project Euler is a collection of 200 mathematics orient exercises. Some of the exercises require large number arithmetics. There are solutions in Haskell and OCaml (in progress). You need to register if want to take part in the challenge.
• IBM Research runs a monthly competition.Problems are given at the beginning of the month, deadlines are in principal the end of each mont, reward is entrance in their hall of fame.