One of the first plugins I installed when I moved to WordPress was Amazon Media Manager. It's a handy way of getting the details of various Amazon products on to your site easily, so that you can link to books, CDs or DVDs you're interested in. It also includes your Amazon Associate ID in the links if you have one, which removes a number of otherwise very tedious steps.
I used it to power the media links in my sidebar for a long time, but somewhere in the upgrade to WordPress 1.5 it stopped working. However, now Amazon Media Manager (AMM) 1.5 is out, and it's fantastic. The new version allows you to search for media within the WordPress admin interface, and select from the results — this is a huge improvement. Many more fields are stored now, so that data like the director of a film is stored separately, and can therefore be displayed separately. There's also a star rating, which is very handy. It also allows you to define any number of different templates for displaying the results on your page, which gives you huge scope to format things in exactly the way you want.
At the moment I'm more or less replicating what I had before (with the addition of ratings stars), but I plan to spiff things up a bit when I get a chance. It's a really nice plugin if you like to write about what you've read, watched or listened to. And who doesn't?