Google built an application out of theirs, and monetized it. Their search engine could also just have been a proof-of-concept, used as a demo in selling PageRan

Google built an application out of theirs, and monetized it. Their search engine could also just have been a proof-of-concept, used as a demo in selling PageRank to another firm. You should investigate patents (preferably with a patent attorney), and figure out just how easy it would be to reverse-engineer your algorithm. Keep in mind that many programmers find the idea of secret algorithms distasteful. Hiding these processes is often a necessary evil in order to make profit, but do not do it if you don't have to (recent example: reddit).