As part of a post-CS161 discussions last week over lunch, we decided that it would be neat to have a tool that would allow you to visually annotate, comment, or file bugs on code snippets. I’m envisioning something web-based with a nicely rendered version of the source on the left and user comments or bugs filed on the right, next to the source, in little call-outs or whatever. Does this sort of thing exist? Anybody?