One day challenge: Building a fun consumer app in 24 hours.
twitter.com
twitter.com
9:45 am: had 24 hours web app idea
10:13 am: Announced it on twitter
10:17 am: Registered domain name
10:24 am: Bought alternate domain name
10:30 am: Setting up SVN repositories and blank django project
10:50 am: Django project structure created, all committed to SVN