You don't have to go all the way to full Common Lisp server-side development. At http://greaterskies.com I wrote in CL the engine that computes and creates the personalized PDF maps of the sky, then built an sbcl custom core that's kept listening to a socket. I then manage the httpd communication with rather simple Python and AJAX, relying in flat files and static HTML. I am quite happy with the maintainability, and I got to use Lisp in the part where I could really take advantage of its power and speed.