On How to Publicize Your Blog's Circulation Steve Rubel says: FeedBurner has launched a new tool that allows anyone with a FeedBurner RSS feed to publicize the number of subscribers they have. I have zero, as you can see below, so didn't work so good for me, but you can try it.

FeedCount is a promotional graphic (commonly called a "chicklet") that displays your feed's circulation - our measure of your daily readership in syndication - that you can use to promote your feed on your site. The circulation number displayed is calculated based on the previous day's circulation total for the feed.