I recently found something interesting in google's search engine known as the Wonder Wheel. Basically, branch map of keywords that are relevant to the original keyword you put in google's search engine. It creates a wheel of clickable links in AJAX format (smooth!) that are relevant to the keyword you're searching for. All you then need to do is click another link from the wheel and it spawns another wheel full of links relevant to the one you clicked. the original keyword I put in for this was 'hair loss'. Using this I was able to brainstorm a multitude of ideas with the few clicks of the button. This is a simple way to brainstorm for new keyword ideas and I have found PLENTY of gems by doing this. All you have to do is search for something via google - on the left hand side there is a 'wonder wheel' link. Click this and you'll be brought to the wonder wheel layout. Hope this helps!