Google as your competition with a product used by almost everyone is probably a little scary. And really a bunch of people have tried it and have yet to find a way to make money.
EDIT:I say pick one field where Google sucks and improve it, make it better. One thing is for sure, you will have less competition by going against Google then by going against Twitter or FriendFeed or HN...
What are your options really? Either charge a monthly fee for a service that your users can find for free elsewhere (either right now, or eventually) or you can slide in ads between the feeds you serve that no one is going to bother to click on anyway.
The big appeal of FeedBurner for most people is their subscriber count monitoring and, unfortunately for them, it's something they don't do a very good job of tracking to begin with.
The other big unspoken aspect of FeedBurner is that those very counts are so easy to manipulate that trusting anyone's numbers is too big of a leap of faith anyway. The whole system is about bunk now.