How do I figure out the subject matter of a given web page ? Similar to what Ad Sense does

I need to figure out what the page content is about. Something like what google adsense does .

For example, If i have a web page about dogs , I need to figure out that page is about ( third party si开发者_运维知识库tes ) dogs so i can suggest dog walking services .

Can i consult an google database or something similar .

This is one of the holy grails of the Semantic Web. There is not one answer. You could scrape the HTML (for example using Python - Beautiful Soup) and submit the text to OpenCalais for analysis.

This is not a task that you want to take on in your spare time - use others's work. Oz