Celestron
A large famous company that offers a wide range of telescopes, binoculars, spotting scopes, and optical accessories.

Deepsky 2000 Pro
http://www.deepsky2000.com
A high powered astronomy object database and log book program.

Lochness Productions
http://www.lochnessproductions.com/index2.html
Planetarium products and other astro-educational supplies. Also, links to hundreds of planetariums all over the world.

Meade Instruments Corporation
http://www.meade.com
A reputable manufacturer of astronomical telescopes and optical instruments for the serious amateur.

Willmann-Bell Inc.
http://www.willbell.com/
Books, charts, software, as well as mirror making kits and supplies.