As the X PRIZE Cup and associated Lunar Lander Challenge approach, as well as the Space Elevator Games and their Tether and Beam Power Challenges, a lot of the traffic here has been for these events. For those new to the site, you'll find plenty of posts on these events, but they'll be mixed with posts on other space prizes and innovation incentive prizes.
If you're just interested in these particular Centennial Challenges, you can filter out the rest by clicking on the tags (below) for the event you're interested in.