Pattern Stories are descriptions of systems that include patterns. Pattern Stories are good ways to learn about a pattern, but they also can teach you about various problem domains.
The PatternStoriesWeb is a wiki clone that contains stories of uses of patterns
http://wiki.cs.uiuc.edu/PatternStories (BrokenLink 20070524)
It is a good place to go if you want to hear how someone used ObserverPattern, or if you want to share your own stories.
EricHuss created the engine, which he calls WikicWeb, but I'm working on the content. Stop by and take a look!
-- RalphJohnson