If you want to be rich, solve search without full-text indexing of sites. Pagerank only ever worked because of human curation of webrings. Full-text search made is easier to find content, and opened the door for spammers. The only viable route forward for search will be to replace full-text indexing with human curation, somehow. Solve how to scale that up instead, so that when everyone else realizes we need it for the health of the Web, you’re ready.