Reddit Mold
Reddit is making some money with this year's gimmick, which lets users punk other users with annoying anti-features such as: gradually eliminating letters the pranked user is allowed to type; gradually eliminating the number of comments a user is allowed to see; and forcing the pranked user to see notes and comments from a special thread called r/basement/.

Urban Airship Revenge
Urban Airship is headquartered in Portland, Oregon, but it powers push notifications and in-app purchases for a hell of a lot of games. UA made its own 8-bit browser-based game today.

Angry Nerds
A spoof of Angry Birds by software developer Atlassian. Merchandise available.

Joel on Coal
A spoof of Joel Spolsky's popular blog, Joel on Software. "I can now announce that my new firm, Port Carbon, has already started work on a new coal mining management product, CoalBUGZ. Ask me if you'd like to be in the beta. And I may as well blather at you, about coal, about mineral extraction, and about energy in general. So here's Joel on Coal."

Helvetica
Google punks font snobs searching for the perfect typeface.

And finally, we can all have the choice to opt out of April Fool's Day in the future with this protocol and Firefox add-on.