One of the things that worked out incredibly well at TechEd was our chalk talks. We had a small theater set up with about 20-30 seats, a whiteboard and a small monitor for presentations. A number of the chalk talks on Windows Workflow Foundation were "steal a chair" events, where more people showed up than chairs. These talks were a great chance to dive deep into some specific areas of functionality, answer questions and head on over to the whiteboard to work through some design issues as well.
Now we have the talks posted on the community site, so check them out.