Yahoo Stores rewritten from Lisp to C++ and Perl http://discuss.fogcreek.com/joelonsoftware/default.asp?cmd=s...

So if you made it to sell it, you might wonna avoid really unpopular languages.

Ruby compared to PHP have a lot smaller user community, but nowadays, one would never call Ruby unpopular.

So there is a different between unpopular lisp and unpopular Ruby

Lisp is not just unpopular, it's also really different from anything else, so harder to get in to.