I have recently been giving a talk entitled "Linux-Fu for PHP Developers" (slides are here) and although it includes some really basic commands, even some quite experienced people have thanked me for particular bits that they picked up. I'm considering dropping some of the sections from this talk so here are the things people most tell me they learned:
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!