wow 'cd -' is a neat trick!..its like windows alt-tab but between directories instead of windows.

You forgot to type just "cd" to get back to your home directory. So the "cd ~"
includes redundant part.

I always knew you could do something like this, but I could never remember how. Perhaps next time
I'll remember :)

You can use minus in other commands directly by prefixing with tilda e.g.
echo ~-
ls -l ~-

You can use minus in other commands directly by prefixing with tilda e.g.
echo ~-
ls -l ~-

For more control, you can try pushd/popd/dirs

nice! I even found out the following :)
Did you know you can also use this for copying files?
$ cd /var/srv/http/projects/foo/
$ ls
.htaccess foo
$ cd ~/www
$ ls
bar
$ cp ~-/.htaccess .
$ ls
.htaccess foo