Learning to Sketch

Are there any sites out there that offer great insight on sketching with hand and pencil? I'm not a natural at all at that kind of stuff, and I pretty much stink at drawing. The only part of graphic design that I'm good at is using the tool 'Photoshop', but I still want to be a graphic designer. But now, I'd like to learn how to do sketching because if I can work with my hands and a pencil, I'm not going anywhere with my dream. So is there any tutorials, sites, and tips out there that can help me reach one of my most important goals; which is learn to sketch well?

Sketching isnt a requirement for GD, but it sure can help.

http://drawn.ca/ <--- fantastic site. Aslo read their how-to section.
http://www.thedrawingstudio.co.nz/blog/ <----- video tutorials (some free)
http://forums.cgsociety.org/showthread.php?t=231354 <--- loomis books (pdf download).
http://forums.cgsociety.org/index.php? <--- massive community, a lot of 2d stuff.