How does the foliage look? When were the plants set out? What varieties? I would say that it's probably the heat. You should have had fruit by now. Without knowing anything else, suggest keep watering and you will eventually set fruit.

too hot. get them some shade and watered. like ed said they will eventually set fruit.

Thanks for the replies! Some of the foilage looks great others not so great. I just trimmed off a couple of dead limbs yesterday. Some leaves are yellowish and curling. 2 of them are Bradleys and 1 Cherokee Purple. The Cherokee Purple has been having a hard time since the beginning. We set them out mid May I think?? Maybe the beginning.. We have picked 8 tomatoes this season and only 1 of them from the Cherokee. We are thinking it's the heat also. We moved them into the shade on Saturday and they do seem to be perking up. Between the three we currently have 5 or 6 growing at this moment so at least somthing is happening. We haven't done anything to them since we potted them either. Should we?

Thanks again!

I agree with the heat as well, but noticed you also said you haven't done anything with them since you potted them... What type of soil are they in, and are you fertilizing them??

Tomatoes (most varieties) will not set fruit when daytime temps are over 90 and nighttime temps are over 70 degrees. While could definitely be other things, too, this is a limiting factor even when everything else is fine.

Here is a link that might be useful: More info