In Firefox you can set Google Reader as your default feed reader. Now when you click on a feed link (or when you click “subscribe” after you preview the feed), you are taken to a page where you’re asked whether you want to add the feed to your Google homepage or to Reader.
If you don’t use your homepage for reading feeds this can quickly become an annoyance. Here’s how to bypass this page & go directly to Reader:
Open up about:config & filter for browser.contentHandlers.
Change the value of browser.contentHandlers.types.2.uri to http://www.google.com/reader/view/feed/%s
Then reset the value of browser.contentHandlers.auto.application/vnd.mozilla.maybe.feed
Restart Firefox. Again select Google Reader as the default feed reader in Firefox’s options so that the value of the previous preference also becomes http://www.google.com/reader/view/feed/%s