While browsing around today, I found a great blog post on how to draw facial expressions. You can find the original article on this site, along with other interesting articles and other tutorials.
Here is a small selection of the drawings on the blog post at DaniDraws.com. You can find the full post with many more diagrams here.

I would also like to thank you all for your presence here on my blog, as without you I would have no audience, and without an audience, I could not have reached the 15,000 hits I have achieved! So thank you!
how come i can’t c your picture, i wanna see it, and btw this is for my art work!
hey,
sorry it seems the picture I was linking to has been removed