I'm starting to get annoyed with people wasting my time.
I'm sitting at YAPC::EU at yet another talk that's overrunning horribly.
Please, people, practise your talks. Figure out how long 20 minutes is. Get the right amount of content for your time.
One low tech aide I've found very useful is to work out the elapsed times on your key slide transitions, then write them out on a piece of paper, along with the wall clock times when these should happen. This way you can quickly see whether you're on track, too fast, or too slow.
It's not rocket science to stay roughly on track, so, please, JFDI.