I'm just interested in if it's really legal for them to be charging for something like this, since they're using google's data for the program. http://www.prprowler.com/
Either it performs automatic querying of the Google site or it is a commercial application that uses the API. Either way, it violates Google's Terms of Service. That does not make it illegal, but theoretically, Google could ban you from using their search engine for the transgression. You can also use Prog for free. It also appears to scrape Google's results against the TOS. The developer claimed in another forum to be working on retooling it to use the API, but I don't see that yet.
what do you mean by "ban you"? if they distribute the tool to other users, it's not like they can ban by IP, and the program could easily just ident as something common like IE... .. so wouldn't it be more or less impossible to "ban it"?
Correct. In simple terms, they could take proprietary action, but it would prove entirely inconsequential. Hence they haven't bothered.
each user would be accesing it from a different IP, and google has no way to tell which IPs are legitimate from the IPs that are using this program, so it'd be close to impossible to stop it, really.