Your mission in an interview is to leave a clear message in the interviewer's head of who you are, and you want to control this message.
When asked to introduce yourself, you can take it as an opportunity to sell yourself and explain your skills and how you get things done, but in all honesty I wouldn't over think it.
The best approach is to relax, try and say something honest and funny about yourself and try and make the interviewer relax (remember they are often not so experienced at interviews).
If you're making a joke, make sure it doesn't make you sound like an idiot.
Tell me a little bit about yourself?
Hi, my name's Dave. I've been programming since I was a little boy and really loved it all the way through my life. My mum used to ration my computer use, but it just made me want to program more. That's what brings me here.
Make yourself stand out but not in an overly arrogant way - give the interviewer something to remember you by and some way to easily describe you.