RSS is a great
technology that not just provides convenient access to information, but
also allows one to make money on information.
Paid subscription.
Some site owners make users pay money for subscribing to their RSS
feeds. Most often, these are the feeds of porno- or crack-sites. Money
is usually collected using PayPal.
RSS advertising.
Any RSS feed can have usual banners (with per-click payment) included.
Besides, you can try to place paid links. Soon, Google Adsense will also
be available for RSS feeds.