If you pass a single minus as the argument to cd, you will change back into the directory you just came from. Ideal for those switching-between-two-deep-links situations.
pushd and popd
I didn't include these in my talk formally but I mentioned them almost every time I gave it (or one of the attendees did!). I don't actually use these commands, but they are like an extension to "cd -" - you can build up stacks of directories and then jump around between them. They sound pretty handy so do take a look.
I got a lot of negative comments for including "cd" and "ls" in my talks - but I had quite a few people say that the -t (to sort by time) and the -r (to reserve the sort) switches were new to . I use these together for viewing which files are new in a directory, great for logfiles or upload directories.
Hope these are helpful to someone, let me know if you use these or have others you'd like to share!