On a similar note for Windows: Everything Search. Blazing fast, super easy syntax, powerful search tools. Almost don't remember where most things are stored on my hard drive these days, since they're all just a shortcut and a few characters away
The built-in Windows search is (for me) abysmal compared to Spotlight search on the Mac, and especially Alfred's interface to Spotlight search. The Windows search seems to switch too early to trying Bing results when I'm only interested in local results.
Never tried Everything before, but I think I've seen it recommended before, so I'm downloading now.