I've always wanted to use FeedBurner. And now that we have our blog up and running, I had this possibility. I signed up with FeedBurner, expecting only very basic functionality; a new RSS link, and some stats about how many people are using the feed. But it turned out to be so much more. I'll give you a run-down of some of the features that I've found cool sofar. I haven't worked with it very long, but some features have already proved very handy.
Firstly FeedBurner gives you the ability to very easily "advertise" your blog on any of your other sites. I before I started using FeedBurner, I was thinking about adding a section on our company website that would display the latest entries from our blog. I was getting ready to do some coding for this, but now I didn't have to. FeedBurner has a feature called "Headline Animator". It allows you to generate some code for a banner that automatically displays some of your latest blog posts. And this banner links directly to your feed. Very handy.
Then, you get to customize the appearance of feed items when people view them in their RSS readers. For example, you get to add links like "E-mail this", "Digg this", etc.
Further, there is a Chicklet Chooser that generates a nice subscription link for you to put onto your blog. This is more visible than the little icon up in the address bar of Firefox, and reminds users that they can subscribe to this blog.
Then there are more features, which I haven't tried yet, but which sound really great. For example, you can let users subscribe to an e-mail of your latest posts, or you can integrate Adsense Ads into your feed items.
So if you have a blog, and it's not on steroids yet, head to FeedBurner, and sign up now.