Apple hosts free seminars and tutorials on a variety of topics -- both in-person at Apple Stores (at least in the USA) and online. You can find in-person events using this page, which has a number of search options. If you'd like to just see the online tutorials, try this page. Simply create an account (i.e. provide email and password) to register for the seminar/event -- you'll get an email with a link to the seminar/event.
There are topics covering everything from podcasting to GarageBand to Motion, switching to the Mac from Windows, Windows compatibility, and much more -- check out the lists at the above links.
[robg adds: Not a direct hint per se, but given I'd never seen either of these pages, I thought they might be worth sharing. There are some good tutorials available, at least in the online realm. I sampled the Motion tutorial, and it's very well done, as you might expect of Apple. The only major complaint I have is that the tutorials are streaming videos, not downloadable QuickTime movies, so you can only watch them when you have a net connection. It'd be nice to have a local library of the tutorials for offline reference as well.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20080501110402308