Harvesting Keywords from the internet

Can you suggest some possible sources to harvest related keywords. One suggestion is to use google and enter in a query and get back and response page and sift through the HTML to get some related keywords. (it might break some EULA though)

This can be made better by using API, but what I see at http://code.google.com/apis/customsearch/v1/overview.html is not enough.

Can you recommend some other sources and what wo开发者_如何学编程uld be a good strategy to design a system which can use multiple sources. I was thinking of using the strategy pattern along with some integration patterns (Spring Integration) to have a modifiable architecture.

My choice of platform is Spring/Spring ROO. I am thinking of giving neo4j a try since a graph database might be a good candidate for a problem where the relationship is more like a graph rather than a table in physical sense.

You're describing Google Sets.

Here is an unofficial API.

You can use the Google AdWords keyword tool. It's possible to query it using the AdWords API without breaking any EULA.

http://code.google.com/apis/adwords/

Another tool I've used it the Big Huge Thesaurus.

http://words.bighugelabs.com/