There is already the tag-closer, and its used fairly consistently in the toolkit (at least I made one swing through months ago looking for places it should be used). But I don't think it addresses the close-tag with no open-tag issue John raises. Someone should look ... I wasn't thinking of that when I last looked at the proc. I think Lars wrote it? If so he'll know off the top of his head.
At Greenpeace we've discussed hooking tidy and OACS together, but not for form verification (good idea, though). We were actually thinking about running tidy against every page we serve in developer support mode. I think having tidy available as an AOLserver module would be fantastic if ... it ... is ... threadsafe!
