One of Android's biggest strengths - hardware diversity - is also a substantial weakness, and the teardown/repair options for such devices is both limited and fragmented. Because there are so many different Android phones on the market, there's no real one size fits all guide for replacing the screen on a Google device. In fact, a lot of newer Android devices don't even have repair guides online. Our search for "Droid 3 Screen Replace" came back with some info relating to the original (and very different) Droid 1.
Buying parts isn't much easier, either. Sticking with the Droid 3, cnn.cn only has one part for this relatively new phone. Other devices, like the HTC Sensation, fare much better, with plenty of replacement part options, and guides to go with them. A new Sensation digitizer goes for just under $70, and because it's a separate piece from the LCD screen (this is not the case with the iPhone 4) you don't need to replace both components if only the digitizer is broken. Check out the video below for a complete Sensation digitizer replacement tutorial.