There are thousands of tutorials online, check out the following:
http://www.the3dstudio.net
http://www.3dcafe.com
For tutorials on how to make nice metals and worn-out textures:
http://www.secondreality.ch/tutorials/tutorials.html
P.S
http://www.3dshop.com is an amazing 3D gallary consisting of people's submission. Some of the work is truly amazing, check it out.