Enhanced Steam offers browser plugins for Chrome and Firefox to add some helpful functionality when visiting the Steam website (thanks and fiftykyu). This page lists the following features it adds to the experience:

• Highlights the games and downloadable content you already own
• Highlights games on your wishlist
• Points out 3rd party DRM on games
• Adds DLC categories to the product page
• Finds out how much you really save on a bundle
• See pricing history for each game
• See how much you've spent on your Steam account
• Fixes the "No Image Available" images on your wishlist
• Displays Metacritic user scores
• Gives you widescreen support information from WSGF
• Adds an "Add to Cart" button on your wishlist items
• Adds an "Empty Cart" button to checkout
• Enhances the Steam Community pages
• User-controlled options page lets you decide which features to enable
• Replaces the Steam Greenlight banner.