I do web development for a living, but my focus is on usability and accessibility, not eye candy. From a usability standpoint, many of the bike mfr websites are horrifying. Some of them are a shemozzle of links all over the place, and it's tough to compare one bike to the next in their lineup.

The Specialized site isn't bad (once you get past the annoying region selector) because they list the bikes in order with MSRP next to them, so you see just how nice of a bike you can afford. Unfortunately, the heavy use of Javascript makes the site rather sluggish, even on a high-speed connection.

This page from Giant also makes it easy to view the line-up, without any slow-loading flash doohickeys. The links for womens models, owners' manuals, and archives are right where you can find them.

Of particular horror is the Serotta website, where you have to pan down the dynamic menu everytime to want to view a new model. The Model Comparison chart is a little better (at least you can click on the bike models in the table to go to that bike) but it's still kind of confusing at first.

I agree with everyone's assessment of Competitive Cyclist's site though. Very nice to use, and speedy too.