xmonad is a tiling window manager for X. Windows are arranged automatically to tile the screen without gaps or overlap, maximising screen use. Window manager features are accessible from the keyboard: a mouse is optional. xmonad is extensible in Haskell, allowing for powerful customisation. Custom layout algorithms, key bindings and other extensions may be written by the user in config files. Layouts are applied dynamically, and different layouts may be used on each workspace. Xinerama is fully supported, allowing windows to be tiled on several physical screens.
Lambdabot is a Haskell development tool, written in Haskell. It operates as a command line tool, embedded in an editor, embedded in GHCi, via internet relay chat and on the web. More information is available at the Haskell wiki.
If you read discussions about programming languages, one topic is quite common: "Why do people use an inferior language like Java/C++/what-the-hell and not a superior language like Lisp/Haskell/Python/you-name-it"?
What should you learn first, Lisp or Haskell? It depends entirely on your personality. One thing is certain - if you want to be a great developer eventually you'll have to learn both.
K. Stengel, F. Schmaus, and R. Kapitza. Proceedings of the 12th International Workshop on Adaptive and Reflective Middleware, New York, NY, USA, Association for Computing Machinery, (2013)
N. Danielsson, J. Hughes, P. Jansson, and J. Gibbons. Conference Record of the 33rd ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages, volume 41 of POPL '06, page 206--217. New York, NY, USA, ACM, (January 2006)