The 70 Percent Solution [the broken link was removed] by John Battelle, an interview with Google CEO Eric Schmidt:
We spend 70 percent of our time on core search and ads. We spend 20 percent on adjacent businesses, ones related to the core businesses in some interesting way. Examples of that would be Google News, Google Earth, and Google Local. And then 10 percent of our time should be on things that are truly new. An example there would be the Wi-Fi initiative.
Google is also well know for the 20% rule for technical staff [the broken link on Google’s site was removed]
Google engineers all have “20 percent time” in which they’re free to pursue projects they’re passionate about. This freedom has already produced Google News, Google Suggest, AdSense for Content, and Orkut – products which might otherwise have taken an entire start-up to launch.
Both models attempt to assure significant time is devoted to new ideas.