If you are looking for Macintosh tutorials, there are some available at these locations:

http://www.apple.com/support/ (look in the bottom center panel)

http://www.apple.com/mac/ (look in the bottom panel)

http://www.apple.com/business/ (Quick Tip of the Week)

In all of the iLife and iWork applications, go to the Help menu and you will find Video Tutorials.

If you haven’t checked out the PodCast area on iTunes, you should. There are a lot of offerings there on just about any subject. Watch them on your computer with iTunes or send them to your iPhone or iPod. Some of the best PodCasts are fromScreenCastsOnline.com and many are free.

Other places to get a few tips and tricks:
http://www.mactips.org/
http://www.macworld.com/topics/mac_os_x_leopard.html
http://www.macworld.com/howto.html