in reply to The Perl Regex Tester
Just an update: As of April 24, 2013, dotCloud pulled the plug on their "free sandbox applications" policy. On the other hand, Heroku still allows single-dyno (whatever that is) applications to run free, so the Perl Regex Tester has moved to Heroku. Its URL is: http://retester.herokuapp.com. Enjoy (while it lasts).
Heroku provides 750 dyno-hours per month free of charge (for now). There are 744 hours in the typical 31-day month, so that means as long as I'm just running a single process, and as long as Heroku doesn't eliminate that structure, the Perl Regex Tester can live there free of charge.
If anyone can think of an organization that might want to support the Perl Regex Tester, possibly by hosting it long-term, please let me know.