If you subscribe to search results, partial feeds, link blogs or other peculiar feeds, you'll probably find it annoying to open the actual page in a new tab. For Google Reader users that also have Firefox and the Greasemonkey extension, there's a script that lets you open the original source in an iframe inside Google Reader. You can either press Shift+V, click on the title of the post or click on the Preview button from the bottom. To open the page in a new tab, press V or middle-click on the title.
This might also come in handy if you want to read the comments or send your feedback.
The original version of this script only works in the "list view" and automatically replaces each feed item with the original posts, but this solution is suboptimal. The updated script works in both views and lets you choose the posts you want to expand inline. Maybe a better idea would be to detect partial feeds or to enter a list of feeds that should be automatically opened.