Pretty much every bitcoin company out there. There's close to a quarter billion dollars of VC funding pouring in and it's very much a global phenomenon in every continent. A lot of reputable companies, two of which have had $150m valuations (the first two on the following list) earlier this year.
e.g. Coinbase, Bitpay, Circle, Blockchain.info.
Mostly engineering, backend, frontend, web &amp; native apps, a fair bit of security and UX, too.
Check out coinality.com for example for lots of jobs, lots of stuff on Angel List too.
Ask HN: Who is hiring? (September 2014)