Any legit/legal binary options brokers in the United States?

The only one I found is Nadex.

Surely they can’t be the only one?

Their platform doesn’t really interest me.

How is Open Binary Options Account - ?

Are there any others here in the US that accept American traders?

Hope these links can help you:
US Binary Options Brokers - Best Binary Options Brokers in the United States |
USA Binary Options Brokers - Best US Binary Option Broker List

TradeRushand Goptions. Both are safe and very popular binary trading brokers which accept US traders. Before dealing with them, read detailed reviews of both brokers.

I used a site called BinaryOptionsCanada, its obviously more for Canadians but they also have Traderush who i’ve tried and they are great.

Via wikipedia I found a site that has a page dedicated to us traders. Go to this us binary brokers page if you are still interested in this.