Some useful sites I found to learn C programming are:
Tutorials:
http://cplus.about.com/library/blctut.htm http://www.juicystudio.com/tutorial/c/index.asp http://www.cprogramming.com/ (Although this site mostly deals with C++)
Another useful site is:
http://planetsourcecode.com/
Which has lots of useful code samples for you to check out and learn from.
Hope that helps a little.