This is so freaking awesome. I've had this problem on nearly every website and blog I've created. Also at both of my startups (Scribd and Parse -- note: Parse uses Swiftype on our documentation pages -- try it out).

I've tried google site search (which sucked and wouldn't index all the Scribd pages for example, and it wasn't good enough for the parse documentation) and I've also used lucene and sphinx (pain to set up and the marketing folks always complained about search results, speed, ordering, relevance, etc, and analytics were a pain). Swiftype is the best option by far. I love this company -- really excited they finally have launched and I can talk about them.

Think about all the sites that use google custom site search just because that's the only decent option for them up until today. Huge market here. Congrats Swiftype.