For a look at amino acid structures and some of their properties, try Image Library of Biological Molecules
The Real Inside Scoop on the forces that drive protein folding (and thus determine the shape a protein prefers to be in) can be found in Principles of Protein Structure course
For a guided introduction to basic concepts in Biochemistry or Molecular Biology (or a host of other biological topics not directly relevant to the stuff here) try the excellent Biology Project at the U of Arizona.
Feeling hardcore? Try the mildly out-of-date protein motions database, a compendium of the types of protein motions that have been deduced through crystallography and the proteins that undergo them. This is largely a listing, not a tutorial!