Swiftype is fantastic. I've been using their service to power search on my Octopress blog since last May when they were still in Beta, and I've loved every moment of it.
Their REST API is also fantastic; I've modified my deploy Octopress rake task to automatically hit the endpoint that requests a recrawl of my site so that the results are always up to date. At first I felt a little dirty doing it, but I engaged them on Twitter (this was last year when I first implemented it, too lazy to find the records) and they actually encouraged it. A great team, and a really awesome product.