The MacTutor Historyof Mathematics archive      Contains many articles on the history of mathematics, including many people and topics in mathematics along with famous curves
The Math Forum      The Math Forum produces a weekly newsletter of notable web sites on mathematics along with a library that archives these sites.  There are also discussion groups and a place to ask questions and have them answered online.
ExploreMath.com     Excellent interactive online animations of graphs along with lesson plans and suggestions for use.
Watch for more links soon.