pushd also gives you simple access via `~-n` in both bash and zsh out of the box. The bonus being that `~-[n]` is correctly handled when used as an argument to other commands too, so that `cp myfile ~-4/` does what you'd expect. The zsh completion for cd functions really nicely for this too, given that you can use zstyle to annotate your entries or group dynamic completions separately.

If you're using zsh you can implement the GPs idea by hooking chpwd, so that you don't need to change your muscle memory on cd. You can even combine them by enabling the auto_pushd option and just carrying on with regular cd whilst gaining access to `~-n` with no other changes.