I actually put this site up last week and tweeted about it then, but for long-term reference I'd like to announce that my Demos site at http://quicksketch.org/demos is now back up and on Drupal. So far I've got demos up for some of the major modules I've writen: Form Builder, AJAX Poll, Image Resize Filter and Insert. I expect I'll add Webform and Flag to the mix shortly.
I personally find the Form Builder Demo to be fun just to quickly construct FormAPI arrays without so much typing. It can be a great learning tool too. Cheers!