I found this not too long ago and was quite intrigued. They recently had some server problems due to too much traffic, but I think their problems have been solved. Anyway, it sounds like authentic, old recordings, and - well you just have to hear it. Basically it is Bob Dylan singing Dr. Seuss... so yeah, its amazing. Check it out at dylanhearsawho.com.
edited on april 23, 2007: It appears that the estate of Dr. Suess did not really like this music leaking the lyrics of our favorite childhood books across the internet and sent a cease order to dylanhearsawho.com - so sad. I downloaded the tracks while they were still up, maybe I can see about getting them to you if you are interested.