How do I find out what keyword a competitor is using?

By knowing a competitor's website URL, is there a way to find out for what keywords they are focussing their SEO efforts on (either organic search or adwords) and what ranking they have for those keywords?

I do know about the google keyword search tool but it doesn't give the info I am looking for.

I think you are looking for things like SpyFu, SEMRush, Keyword Spy, and Hitwise.

I don't know of a direct way to figure that out but testing keywords on google and seeing if your competition pops out in the paid links or even in the Organic results.

You could potentially use an SEO tool to check for keyword density of your competitors page. If they have done their job right they should target those specific keyword in their page.

Try this one: http://tools.seobook.com/general/keyword-density/ put your competitors web address and check which keywords come up the most, it should be what they are targeting.

The difficulty would be with long tail terms, which, by definition are not that common.

Cheers

You can try the Google Trends for website tool: http://trends.google.com/websites?q=wikipedia.org It gives popular search terms for a given site.