I rewrote searchamazonprime.com to make it better. It's designed to find products on Amazon.com that are eligible for Amazon Prime free shipping. To do this, it finds only products sold by Amazon.
The new site is redesigned to look better, and the back-end is much faster than the old one.
I've also added some nice features. It finds many more products than any other Amazon search site that I know of, and it shows them on one page.
There are sections of results by category, and you can hide categories you don't care about.
I wrote a spelling suggestion corrector based on product names. So now when you type in a misspelling or a typo, you get a suggested correction, like on Google.
Finally, you can now add searchamazonprime to your Firefox search bar. If you use the search bar in Firefox, you will get auto-completion style suggestions as you search.
It's really easy - and there's step-by-step instructions here.
So if you have Amazon Prime, or buy a lot of stuff from Amazon.com, try it out, and let me know what you think.