A big one few people think about is Africa.
The fact that M-Pesa is so popular and they are used to paying for things with their cell phones makes it a simple transition.
Kipochi :
http://motherboard.vice.com/blog/one-third-of-kenyans-now-have-a-bitcoin-wallet
But the fact:
Kipochi is dead.
There is only one person who sells bitcoins via Mpesa/cash in whole Kenya on localbitcoins.
Kipochi is weird... does seem to be dead, but still appears in the news. They also have had quite an active twiiter feed (at least up until a week ago.. that also seems to have gone quiet...)
But there is also BitPesa that seems to be taking a stab at remittances: http://www.coindesk.com/bitpesa-uses-bitcoin-slash-kenyan-remittance-costs/
Who knows whether they will go the same route as Kipochi? But I think the point is that M-Pesa integration and African remittance opportunities are still viewed as a large potential market, just waiting for someone to make it all work.