Sober Secrets is a fast and free application to keep secrets from your (drunken) self. Sober Secrets makes you correctly and timely solve a math problem before it will show you it’s hidden notepad. Use it to store your ex’s phone number, the number to that “oh so bad for you but oh so good when you’re drunk” delivery place, or even the recipe to your favorite dish (one should probably not use the oven when inebriated). Just make sure you can answer in under 8 seconds when you are sober!
Update 4/2012 This is now open source and hosted on GitHub. Check it out at my GitHub page.