I think Nodejs gave JS a big popularity boost.
There are at least half a dozen somewhat related projects: nginx_lua, tir2, luajit.io, luanode, tarantool, lusty, plus a bunch of libuv bindings.
And yeah, a single lua 'killer app' could do a lot for the language's popularity (elua comes close, but is a bit niche).
I think Nodejs gave JS a big popularity boost.