I'm totally fascinated by game economies as they generally approximate real economies but usually have "faked" aspects because game economies usually lack feedback loops that real world economies have. Blah blah blah I am not an economist so I'm kind of fudging my English here blah blah blah. Regardless, I still find it really fascinating. I also find game weather systems really fascinating.
Anyhow, there's an entry on issues in the Star Wars Galaxies economic system that led them to discover cheating. It's detailed here. There's some more information on it here.