Seriously, anything. I use Haskell for any scripts, e.g. crawling web sites. (Python's position has been taken by Haskell in my toolbox.)

Surprisingly, a task as simple as web crawler can be related to so many concepts: regex, parsec, optics, conduit, concurrency, I/O...

The fun of programming Haskell is often you introduce a higher-level concept to your program to make it faster or more generalized, but the code gets shorter and more functional! Wish you a happy Haskell journey and find Haskell fun as much as I do. :-)