You’re probably familiar with that calendar that is included in the Windows Task Bar, or maybe the one included in your email client. Those are all fine and good (enough to nearly drive printed paper calendars to extinction), but they aren’t geeky. If it were up to me, these desktop calendars would have a video game theme.
For this example I enlisted Super Meat Boy, a game that has a perfect 5 x 7 grid in its world maps. This design has all the ingredients of a calendar you’d expect in a Calendar app, but with a few video game wrinkles; like the character would be seen on today’s date (probably in an animated cycle).
You could add events as well (events are marked by Band-Aids for the SMB calendar shown above). There would be pop-up windows if you want to see an event breakdown.
Another game that would be great for this is Super Mario 3, which I’ve used often for maps. The numbered levels in that game’s world map would make for great calendar. Basically any game with a world map can be used for this type of calendar.
Dave's Geeky Ideas 
Hmmmmm. Would be a great addition to a video game theme’d phone, and shouldn’t be too hard to create as an app I’d think… Course, every game would require a different app, customized, but still.