Jon Scott's Site - A great web site from another home automation enthusiast.

Smart Home - Good site for home automation gear, especially X-10 modules.  They have their own line of high-quality X-10 modules.  Not always the best price.  For many things, shop around on the web first.

Xantech - A manufacturer of some very good home automation equipment.  I especially recommend their IR components.

Custom Solutions, Inc. - Makers of the awesome Home Vision Pro home automation controller.

Channel Vison - Manufacturer of home automation audio and video gear.  I have had good experiences with their video modulators.

Worthington Distribution - An excellent home automation e-tailer with great prices.

Hometech Solutions - Yet another home automation e-tailer I have used.  This is where I bought my Xantech amp.  The initial shipment was the wrong amp, but I received excellent service getting it resolved.  I have ordered other things without problems.  This site also has some how-to pages.

Applied Digital - They have a less expensive home automation controller called the Ocelot.  I have not used it, but a lot of people recommend it.

RCS - Manufacturer of X-10 and serial controlled thermostats as well as other things.

James Lipsit's Site - Another excellent site about a guy's home automation system.  James uses speech recognition in his system.

Girder - A powerful bridging software used to control windows applications.  I use it to control media player and for text-to-speech via its serial plug-in.

HouseBot - PC-based home control software now owned by Meedio.  Not free any more, but still less expensive than many and has a very good design.  I plan on using it for control of my touch panels.