Helium - Helium lets you accept payments by credit card for anything you want to sell online.
Reddit List - Tracking the top 5000 subreddits
Product Hunt Shell - A geeky, web-based shell for browsing Product Hunt
Reddit Check - A tool to check if a URL is on Reddit and going viral
Screen Commander - Blank your screens at the click of your mouse.
University of Reddit - Learn 1,000's of new things, from reddit