Adds a "Preview button" to Google Reader that allows you to view actual article in a frame. Clicking again on that button goes back to RSS view. Does work both in List view and expanded view.
A great list of 15 "hacks" for Google Reader using Firefox. includes previewing the original site for a post in the reader and other useful integrations.
iReader is a browser extension (for both IE and Firefox, and on PC or Mac) that lets you preview the content of a link, before you click on it. It's similar to the web previews products we reviewed back in January - Browster, Cooliris, Snap, and Sphere