if you like vertical spreads probably you would like their spreads, if you are a day trader. Nadex has two completely types of different contracts. Once of them is binaries as discussed. The other one is spreads. IMHO Why are these better than vertical option spreads? They are cheaper so you can better ratio your size to your risk. They don't have a week or month etc.. till expiration so you pay less for time decay.. this also results in much higher delta and much higher gamma. You can do them nearly every single hour 2 hour expirations, 5, 7, 23.5 etc.. hour expirations so there is almost always a low risk spread trade with low theta high delta and high gamma. This is much better than trying to day trade a vertical option spread as you will make more per dollar risked with the higher delta and gamma (they use a simple black scholes model) I use these for larger expected moves or to do a straddle before a news event where i have the stats on the expected move based on historical moves on that instrument for that announcement.
i'm looking at opteck, optionbit, optionsxo, and regal options. This is out of a list of 40 brokers (and growing) which take US customers, have range and no touches etc.
Any dealer willing to take US clients is going to rip you off. Those dealers are shit and only allow you to go long digitals and touches.