I'm playing with Git in isolation on my own machine, and I find it difficult to maintain a mental model of all my branches and commits. I know I can do a git log to see the commit history from where I am, but is there a way to see the entire branch topography, something like these ASCII maps that seem to be used everywhere for explaining branches?

      .-A---M---N---O---P
     /     /   /   /   /
    I     B   C   D   E
     \   /   /   /   /
      `-------------'

It just feels like someone coming along and trying to pick up my repository would have difficulty working out exactly what was going on.

I guess I'm influenced by AccuRev's stream browser...

Use git log --graph or gitk. (Both also accept --all, which will show all the branches instead of just the current one.)

For branch names and a compact view, try:

git log --graph --decorate --oneline