I found out about codepad while reading about Haskell. Like pastebin, it’s website for posting snippets of sourcecode to show people. It has all the basic functions that pastebin does: syntax highlighting, line numbers and (somewhat) private posting. However, codepad also allows you to run your code through a compiler/interpreter and return output and errors along with your code. It has a number of major programming languages available, though pastebin wins by a long shot in terms of coverage (obviously, codepad provides compilers/interpreters). This looks like it’d be very useful for collaborative debugging.