I often get URLs in Adium and other places that were pasted from Firefox which leaves them incorrect by html-encoding the URL. This results in "http://foo.com/?bar&baz"; rather than "http://foo.com/?bar&baz";

A simple regexp substitution could fix this; allowing a generic external rewrite API would be even better.

As a workaround, I'll see if I can write an app that accepts such URLs, and sends the corrected ones back to Choosy; then I can have Choosy send them to it rather than a 'real' browser…