Superstring web sites:

The Second Superstring Revolution,  report on the latest developments in superstring theory
"Superstring Theory" by Brian Greene, Cornell University
"String Theory" by Robbert Dijkgraaf, University of Amsterdam
A World of Strings, from www.hypermind.com (advertisement?)
Stephen Hawking's Universe, web site based on the PBS series has info on strings
String theory in a nutshell, has a small collection of essays on string theory
Superstrings and fundamental theory, part of a larger and very nice web site from the Cambridge Relativity