I've added a new entry to the Hacking Wishlist. This one I was racking my brain a little on last night, but couldn't find an elegant solution. It's probably obvious though.
I want a sed/awk command (probably awk, actually) that can take a stream and a regular expression and move all the lines before that regular expression to the end of the file. Sounds simple, but for whatever reason, I haven't developed a solution! I need to brush up my awk skills!