Option one: you can give them a call. If someone says they are going to call you, and they don't, policy says that it is okay for you to call them. After all, once they dial, you are connected, so how does it really matter who does the dialing? Of course, if you call them instead of waiting for them to call you, it might look a little desperate. It might also give them the wrong impression, or make you seem like you are coming on too strong. Of course, it might also be to your benefit. For example, maybe they weren't sure if you had a real interest, and chickened out on calling you. Thus, you make things a little clearer for them by initiating the call. You have to decide if that is a risk you want to take.

Option two: you can move on. If he says he will call and he doesn't, then there is a good chance he wasn't really interested, and was just trying to spare your feelings. Of course, you have to consider the details. If he knows where you are, who your friends are, etc. and could get a hold of you if he wanted to, and doesn't, then move on. This is probably the healthiest option, and chances are if you meet up again, you can stand tall knowing you did not wait around for a call. If you are just not the kind of person that can move on, and have to see it through, and get rejected outright, then this option is not really for you.

Option three: you can arrange a "run-in" and see what they say. Generally you have common friends, or at least some kind of info about the person that would make it possible to see them at some point in the future. Maybe you know where they work, or you will be attending the same party. So, bump into them and see if they make an excuse, or just neglect to mention it. If they don't bring it up at all, it means they intentionally did not call you. If they make an excuse, they may have wanted to, or maybe they are just being nice. Either way, do not be the one to bring it up, and don't ask them to call, otherwise you look bad, and then they will be glad they never called.