I have a site that is using frames. Is it still possible from the browser for someone to craft post data for one of the frames using the address bar? 2 of the frames are static and the other frame has php pages that communicate using post. And it doesn't appear to be possible but I wanted to be sure.
No, it is not possible to POST data from the address bar. You can only initiate GET requests from there by adding params to the URL. The POST Body cannot be attached this way.
Regardless of this, it is very much possible to send POST requests to your webserver for the pages in a frame. HTTP is just the protocol with which your browser and webserver talk to each other. HTTP knows nothing about frames or HTML. The page in the frame has a URI, just like any other page. When you click a link, your browser asks the server if it has something for that URI. The server will check if it has something for that URI and respond accordingly. It does not know what it will return though.
With tools like TamperData for Firefox or Fiddler for IE anyone can tinker with HTTP Requests send to your server easily.