http://gclimbing.com is not really a failed idea, more like a failed project. Some years ago, I administered a shared climbing blog in Austria. After some time, nobody was using it anymore (It was quite complicated to use). I wrote a new software and put it online, which is gclimbing.com - but it didn't really take off. Everybody was on facebook by that time.
Another idea I tried was http://scribblingspree.com - A player would draw a picture, the next would describe it, the next one draw something based on the description. This started as a project to practice wicket and javascript. It was just not that much fun to play after a couple of rounds. Note that I did not know DrawSomething when I wrote it.
I leave both projects online so I can link to them from my CV, but otherwise both are pretty much dead.
Edit: Oh, and I forgot: http://davidtanzer.net/node/82