I would commend a blog post by Stephen Arnold on the future of paid-for web search, prompted by the release of Neeva which comes free for three months and then you pay $4.95 a month. (That fee is in very very small print on the home page!) Over the years several companies have tried to take on Google, notably Exalead, and of course Microsoft. A lot of potential here for the research community to carry out a host of A/B tests on Neeva vs Google. Incidentally if you have not come across Stephen before he is a very well informed (and usually highly sceptical) watcher and analyst of the search business. Some years ago now we co-authored a guide (actually quite a large report) about the successful management of enterprise search but it failed to make the best sellers list. Indeed it failed to sell at all!