I've been buying from Amazon.com for awhile now because it's completely painless!
They carry everything under the sun. That's right not just books any more, and the service is outstanding.
My latest purchase was a battery powered line trimmer. Not only did they offer more brands than any other site I found, but they had user reviews of all the products. A huge benefit IMHO.
Amazon offers all the online ordering necessities that you would expect from a good online company including real-time inventory status, upfront shipping costs, firm shipping dates for out-of-stock items, credit card billing delayed until ship date, and confirmation emails for every step of the transaction.
It's truly an easy and worry free place to shop.
I'd like to say that they have the lowest prices but I can't because in the case of the trimmer, they seemed to be the only place that carried the brand that I wanted. However, they did offer FREE shipping!
The only thing I disliked about Amazon was paying taxes, which is required since we are both in Washington State.
A quick update about Amazon.com. As easy and convenient as it is to shop there, I'm finding that they are not very competitive (on price) in the home electronics market.