Source Tree Visualizer is an open source project that visualizes source control repositories as real growing trees. It started as a research project at my former startup Discursive Labs, but we felt it was too cool to let sit around somewhere on a hard drive.
Part of this project was to visualize the most popular source repositories on github and google code, etc at the time. Some of these turned out with really interesting features and tall branches, etc.
Check out my Google+ gallery of some of the more popular source repositories:
Check out a video of a tree being built:
You can get the latest code, examples, media, etc from the github repository here. It’s all BSD licensed, so you can use it most anywhere