Wow. Lots of stuff going on in the Central community the past couple of days. First of all, a new Central community site has launched. CentralMX.com already has a ton of information and news, and has plans for tutorials and forums.
Geoffrey Williams released a beta of his Amazon application. This is a very advanced app and you should definitely check it out. You can see screenshots here and here.
Finally, Mike Lyda release a Central application called FiRe, which is a find and replace utility. Check out the page as he has some good information on how he developed the app.
I expect that we will see a lot more of this type of stuff once we release the SDK. Stay tuned.