After dabbling with it for a couple of weeks, I wrote the backend (search & indexing implementation using the Go standard library's suffix array implementation) of our websites' autocomplete feature. It's been running for 7 months without a crash and without leaking memory, serving several million requests/day.

I'd like to use it more, but we have so many layers of legacy Perl code, that it's difficult to replace single components because of their dependencies (rewriting anything worthwhile would mean rewriting 4-5 libraries also).