Not to be pedantic but Snapchat is actually from LA and they're very proud of this fact. In the VC context, they did take money from (Silicon Valley) VCs, but their origins and workforce isn't from SV.
Being even more pedantic, SnapChat started in a class in Stanford. They moved to LA because that's where their early users were and where they started to go viral.
(Of course, being equally pedantic about other Silicon Valley companies - Facebook, Reddit, Dropbox, and YCombinator all "started" in Boston, and the critical events in both AirBnB & Twitter's history happened at SXSW in Austin.)
One of the last consumer-facing, blockbuster level startups outside of SV (or California) that comes to mind was Groupon. But I don't consider them to be that great; kind of a fad that took off for a while and is now lingering. When I say blockbuster level startup I mean something that becomes a household name used by mostly consumers. Highly visible companies mostly. I lump LA/SV together because they're in the same state, and there seems to be a lot of inter-funding between the two areas. But I'm also from Chicago so maybe it's just me. Hah.
I'd argue that question, the way it's phrased, is very revealing the advance of tech and the things enabled by tech don't begin and end with smartphone apps. There's a pretty strong social/web/app mindset to the SV lens today and it causes a lot of people to undervalue and overlook what's happening elsewhere. For example, as other have mentioned, biotech/pharma is huge in places like Cambridge and is barely represented in SV.
I used the term "app" but I really meant company. But the important term in the question is "blockbuster". If people are undervaluing and overlooking what's happening elsewhere it's because those things aren't blockbusters. Biotech/pharma companies have been pretty disappointing in terms of blockbuster discoveries. Maybe CRISPR will change that.