From the about page:
SymbolHound is a search engine that doesn’t ignore special characters. This means you can easily search for symbols like &, %, and π. We hope SymbolHound will help programmers find information about their chosen languages and frameworks more easily.
SymbolHound was started by David Crane and Thomas Feldtmose while students at the University of Connecticut. Another project by them is Toned Ear, a website for ear training.
I first saw SymbolHound mentioned in a discussion of delimiter options for a future XQuery feature.
For syntax drafting you need to have SymbolHound on your toolbar, not just bookmarked.