Good, functional sites that make it easy to get the info to where it needs to go.
Ditto times elebinty bazillion.
Flashy, spastic, grandiose websites are great for marketing... and SUUUUUUUUCCKK as electronic storefronts. If you want to use them for the marketing side of the eStore, great. Knock yourself out. But ditch the interactive windows, sliders, cute little pop ups, and "can you believe how neat this is" features on the product selection / customer interaction pages. High-zoot whizbangery on that page is distracting, confusing, and generally just annoying as hell. Make the product selection and payment pages simple, straightforward, obvious, and intuitive. Lemme pick the damned item, select any options, and pay for it without having to learn the frakking page controls, or dealing with your version of Microsoft Clip popping up all over the place and bugging the crap out of me. Follow-me dialog boxes should be punishable by death.
Example of how to do it wrong (product selection is confusing and it is very, very, very easy to not get what you think you've selected):
www.v2cigs.comExample of how to do it right:
www.amazon.comBrad