I am noticing now that where ever I go that that Google nows who I am an shows me the same sort of ads irregardless of what site I am at (most times). I think google is mistaken if it thinks I'm forever going to click the same type of ads especially when I go to a different site to view different content. Now I notice I can't change the content of adsense on my own sites without a large degree of difficulty because google says it will show ad content relative to my site but is that what google is really doing?
I suggest you put more meta keywords for your site/blog so that Google system can display more ads that related to your sites randomly. Also, add more content to your site will help too.