Academic:
The National Science Foundation
The NSF homepage with links for Summer REU programs.
Information on chemistry careers and much more.
The site includes reprints of many of the great historical papers in chemistry. It makes for fascinating browsing, and may also be useful for students preparing for the GRE, which does include some amount of chemistry history.
An online searchable database, very useful for CHE 327, 333, 334, 383, 384, and 385 students.
A very large variety of chemistry sites you may research that's provided by yahoo.com.
An excellent resource to obtain information on chemical compounds.
Find almost any reaction you have ever heard of!
Amusment:
Comic book
Style Periodic Table
Have some fun while learning chemistry.
Interactive table of isotopes plus funky periodic tables, and history of the periodic table