Since moving to San Francisco and talking to people about joining the tech industry, I've been asked several times "so, what would you find it exciting to work on?" When I answer "feeds - you know, RSS, Atom that kind of thing" I invariably get a blank look. Maybe if I develop my thoughts I'll do a better job communicating my enthusiasm.

I use a feed reader daily. I use it to keep up with blogs that I'm interested in, of course. I've written before about how it changes the definition of a high-value blog, from high-volume to good signal to noise ratio.

That's the canonical geek use case for feeds. It's not going to take the world by storm, even with simpler tools.

But there are other things I use feeds for. I use them for anything that I want to check regularly that has a feed available:

• My friends' Flickr photos (based on my Flickr contacts)
• Comments on my Flickr photos
• Local events (based on my last.fm profile)
• Comments on MetaFilter threads that I care about
• Trips my friends are taking (through Dopplr)

This is starting to look a lot like Facebook, right? And one way to look at Facebook is a feed reader in a social context. The design is nicer than MySpace's, but what really distinguishes Facebook is that central news feed. "Like" is a really simple method of subscribing to a feed, and becoming friends with someone subscribes you to multiple feeds about their activity.

Facebook's popularity means that hundreds of millions of people are looking at a feed reader every day. Many of the applications built on the platform are only possible because it's such a good interface for consuming feeds. Suffice to say I don't think Facebook is a fad that's going to die out. People's activity online is increasingly going to revolve around subscribing to, consuming and interacting with feeds.

But short of building a Facebook competitor, what are the opportunities for cool new applications? Watch this space.