The website Poll Everywhere allows users to sign up for a free (limited) account and run an SMS poll of up to 30 votes per poll. For projects requiring higher volume capabilities, they have monthly plans going up to 10,000 votes ($370 a month, no contract) and they offer custom plans for even more extensive needs.
From the Lifehacker website:
Need to know how many folks coming to your big bash prefer beer, wine, or soda? Poll Everywhere offers a free polling service that lets you send up to 30 SMS messages with simple reply instructions to gather opinions. You can also send a link to your polling page by email, Twitter, or whatever service you’d like, but the convenience of having to text less than 10 characters back likely boosts your return rate. Poll Everywhere’s free plan doesn’t let you see who exactly voted for what, but it could come in handy when you need a small group’s opinion.