blam! has become a templating tool for writing reviews of (so far) books, CDs and DVDs.
You enter the ASIN/ISBN number of the item you're reviewing, then fill in the name and URL of your weblog, your Amazon associates ID if you have one, and your review.
blam! uses Amazon's web services to look up the metadata for that item, then produces the HTML you need to paste into your weblog, including an image of the item, referral links to Amazon, and metadata that will allow sites like allconsuming.net to pick up your review (like this one).
As an added bonus, your review will also be posted to blaxm! for anyone to read, where it will be organised by category so you can find other people writing about the same things as you. There are RSS feeds there as well, don't worry. Your associates ID will also be passed through to the blaxm! site, so you can get commission from referrals there.
You can launch this blam! bookmarklet from any book's Amazon page to begin writing your review.
Update: Fixed the bookmarklet so it launches from any Amazon book, CD or DVD page. Also it now opens from any page so you can add the ASIN number yourself.