If you use an RSS reader it should have the ability to export your subscription list in a format called OPML. 

The subscription list contains a set of information about the feeds you follow, most important being the URL of the RSS file that contains the items of the feed. 

Here's an example of a subscription list, a set of feeds about Major League Baseball.

It's important to be able to export your list so that:

• You can switch to a different RSS reader if you want.
• If you want to share your subscription list with a service that combines your list with those of other people like you and provides recommendations based on the feeds you already follow.

I am hoping to start a new service that shares feed information called Share Your OPML. It's a reboot of a service I had in 2006 which was quite popular.

There's also a technical description, which is part of the OPML spec.