Firefox plug-in that automatically sends the pages you visit to an HTML validation server. This lets you validate dynamically-generated pages locked away behind complex logins. You can tell it ignore certain types of errors, and the website aggregates information about what types of errors are commonly ignored.

Annoyed that Firefox pops up the source of a page in a separate window when you View Source? Annoyed that Epiphany shows the source of a page in Gedit? Help is at hand! Simply drag the following link to your bookmarklet bar: