I just finished developing a web app with mochiweb. I started out porting one of our applications over to erlang but due to time constraints and my lacking knowledge of erlang I ended up just wrapping a php application in it to make use of some of the features of erlang. From my initial implementation though I was quite impressed at the ease of use and am definitely considering it for other applications in the future.
http://weblog.miceda.org/wp-content/uploads/2009/07/build_we...