I dropped my iPhone earlier today. The screen is now full of cracks but the phone still functioning. Is there any cases of DIY style repair being performed? Can anyone share their repair steps for this?
I went through this myself a couple of weeks ago. Stupid tile floor in my office wouldn't catch my phone at 9.81m/s2. I ended up taking my phone into a mobile repair shop and had them replace the screen (voiding my warranty in the process), but was a hell of a lot cheaper than doing it myself. Took all of about 15 minutes.
Your profile doesn't list where you live, but any Apple Authorized repair shop can do it for you (or send it away for repair if they can't do it in house).
That said, it is possible to do the repair yourself. iPhone 3GS glass replacement kits can easily be purchased on eBay and from any other number of resellers. The process for doing it yourself isn't easy, but depending on your own level of handiness, you could do it yourself.
There are some excellent video guides for DIY iPhone glass replacement on YouTube. For example: http://www.youtube.com/watch?v=4mboB8p-sdw
eBay is a great option for repair kits, you can get them sent globally no matter where you are. Unless perhaps if you are a Nigerian businessman....
Otherwise you can choose an aftermarket iPhone screen repair service, if you are in Perth then www.buddhaiphonerepair.com is a fantastic way to go.