You can buy ads in RSS feeds. Theoretically it is a way of reaching the subscribers of the RSS feed. Some ezines and bloggers have over a 100,000 subscribers.

The problem with feed advertising is that it is pretty hard to measure ROI, atleast in my experience. You invest your precious advertising dollars, but you can't really be sure how much traffic or revenue it is generating.

For that reason, RSS feed advertising makes sense for branding purposes.

NOTE: when I say RSS feed advertising I literally mean placing an ad on a RSS feed. It has nothing to do with a blogger doing a write-up about your company or product (which can be delivered over RSS).

Not everyone can advertise on the Feedburner advertising network. It is by invitation only, and advertisers are selected based on:

- how long Feedburner has managed your feed
- your subscribership size
- your frequency of posting

Feedvertising allows you to run text link ads in your RSS feed. Apart from the Feedvertising ads, you can also choose to run your own in-house ads or affiliate links.

Pheedo is an advertising platform converts your RSS feeds into rich, dynamically updating advertising that engages your audience…Pheedo retrieves your RSS feed several times an hour and updates your FeedPowered advertisements with any newly published items.

Participants of the Yahoo Publisher Network program must have a valid U.S. Social Security or Tax ID number, and web site content that is predominantly in English and targeted at a U.S. user base. Yahoo! will contact you about your eligibility to participate and about availability of the program.

Q-Ads is an advertising network that frees writers from traditional constraints in advertising. Q-Ads delivers relevant advertising, based on user defined keywords, as image based text ads that can then be used on websites, in blog posts, and in RSS feeds.