Jeff Galloway is a well-known runner and author who promotes a running program that I believe C25K got its principles. He advocates running injury free until you are 100 (I guess after that there are no guarantees). I have read a couple of other community members mention they've purchased his book. Here is a link to his site: jeffgalloway.com/ If you click the Resources link you will be able to read many of his previous articles and tips.
For those who are interested in increasing their speed, I previously posted a link to 5 Tips provided by him. Here it is: active.com/running/Articles...
Jeff lives locally in my area, and is co-sponsoring a 5K Corporate run/walk with Kaiser-Permanente Healthcare in September. This will be the first time I plan to run the entire distance in one of these types of events (I have previously done the Bay to Breakers Fun Run in San Francisco, but walked) The cool thing is that it provides an 8 week training program to get prepared. The training starts this coming Saturday. Perfect timing for me, because I just completed C25K yesterday.