I own www.csstalk.blogspot.com it's currently pr2. I don't use it anymore... gets around 2-10 uniques a day from search engines, when I used to post it was getting 30 + a day....
That's pretty much dead.. do you plan on updating it anymore? If not just leave adsense on there (I would move your ad to the upper part of the page..).
Leave it as it is. You have nothing to lose by keeping it there. In the future it might be useful, you never know.
Sell some blog posts or links on the cheap. Another idea would be to locate a product or service that's targeted to your visitors and just make the blog one big sales letter for it.