My school offered the opportunity to study Computer Science for GCSE. Like the rest of my class I made first a game then a puzzle using Java for my controlled assessment. I didn't just wait to learn Java with the rest of the class - at that time I played Minecraft quite a bit and I discovered I could make plugins for Minecraft servers using the Bukkit API. This served as a really helpful introduction to application development and really helped with the previously mentioned controlled assessment as by that stage I knew a lot more Java than the rest of the class.
Outside of school, I made plugins for Minecraft. My main project which helped me learn so much is still available for download, having been downloaded over 23,500 times from the official link on the BukkitDev site. If you're interested in finding out more about this, have a look at the SpectatorPlus project page on this site.
For my A Levels I studied Software Systems Development, for which I made a quiz using C# and Windows Forms. The similarity in Java and C# syntax helped greatly, as I was able to work out a lot of C# code just by knowing Java. The quiz, which I called Code Quiz, was based on GCSE Computer Science as it was a subject I felt I could confidently ask questions about, having already studied it!
I also enjoy Android programming. I've already made some apps but none of them have quite made it to production yet! You can see the Android section on the projects page for more details on this.