I've done some geeky things in my day, but then there's today.
Today, in my sci-fi tabletop roleplaying game I'm refereeing, that I wrote the rules to myself, I let my players use their iPads or iPhones to connect to a web application I wrote which emulated the actual sci-fi personal data assistant their characters use in the game world.
Let me reiterate this so it sinks in. I wrote a web application for fictional people to use on fictional devices. For a sci-fi tabletop roleplaying game. I am geek.
Here's the thing, though - it was a hit! The campaign is about unraveling a mystery about a murdered friend in a dystopian future, and this allows the players to investigate, analyze, and explore on their own, in a way that evokes the setting. The web app tracks the leads that the characters can follow up on, provides background information about the game world, and gives them a way to "receive data files" from characters. For instance, I was able to drop in new leads on-the-fly using my own iPad as they appeared in the story. It worked really well; the players were using it practically the entire time.
In fact, they're requesting new features for their in-the-game-world PDA. I'm about to get even more geeky - I'm going to be a fictional software developer responding to in-game-world software update requests... Gah!