Feedburner lets you track your feed-stats.. plus it has a lot of other nifty things like graphics that show your number of readers, etc.. it's free and it's good.. i recommend that you use it..
show number of subscribers and other stats..cute buttons for your blog's rss feeds....it takes wordpress's default feed link as input and creates it's own feed link with which your users would subscribe and u have info abt them....
Feedburner also adds widgets that let you add quick links to every post on your blog as well as feed, making it easier for your readers to Digg or add the post to del.icio.us. The Feedburner Ad Network also monetizes my feeds much better than AdSense for Feeds ever did, and also offers ads for your blog as well.
There's been some controversy about their services, but I personally haven't experienced any problems. They have a free service as well as an upgraded subscription...I think it's worthwhile to give it a test run.