To install, just run something like this:
cd ~
git clone git://github.com/JesseAldridge/simplejump.git
echo "source ~/simplejump/shell_part.sh" >> .bashrc
You will need to modify shell_part.sh is you use a path different from the one I use.
Then restart your shell and you're done.
Now, after you cd to a directory you can jump back to it with z <partial name>.
Example:
$ cd
$ pwd
/Users/jessealdridge
$ mkdir -p foo/bar/baz
$ cd foo/bar/baz
$ cd
$ z ba
$ pwd
/Users/jessealdridge/foo/bar/baz
When multiple results match, simplejump guesses which directory you want based on the number of times you've accessed the directory, how recently you've accessed it, and other factors.
This project is mostly a clone of z (https://github.com/rupa/z).