Are you a Twitter fan? Hehe .. I am, lately 
This cool project monitors Twitter for specific things like a new tweet, tweets that contain a specific hashtag and when it fires … well .. the monkey starts flapiing its arms … just take a look.
If you plan to measure the distance you can always use a cheap infrared distance sensor like Sharp GP2Y0A02.
It is really easy to make an interface to it using Arduino.
Sharp GP2Y0A02 - infrared distance sensor - Arduino
A twitter posts reading robot .. what would you want more if you are a heavy Twitter user? It seems simple to build + you have all the source code included
Wow .. I remeber playing Hangman a lot when I was a kid. I always loved this game
Now .. it is still interesting if you create it for your hobby, by using an Arduino and an LCD display. Think on how cool gift will it be 
Here is a nice project that shows you how to create a speed detector with only an Arduino, one normal resistor and two photo resistors. Also .. full code included
