What software or freeware do you use to analyze the keyword frequencies of the top words on a URL? Any suggestions?

Do you mean the keywords that visitors use to find your site through a search engine? If so, then Wusage 7.0 does this for you. It gives you detailed table/graphs that tells you which keywords were used to find your site and from which search engine.

Slightly off to the left, but http://www.AnalogX.com has an interesting utility for keyword monitoring.