I had come upon this technique sometime ago but with the recent change in the way Technorati looks, I wanted to document the link since it still appears to work. You can use the following URI to generate a PNG with incoming links to your blog for a given period using Technorati. There does seem to be a maximum number of days Technorati keeps track of links and that number is less than 365, closer to 200. Just change the BlogURL value to the URI of your blog, and modify the size of the graph as you see fit for your blog or application.
I come up with the following graph for WeblogToolsCollection.com