I have bought numerous audio and video Teaching Company courses and have never been disappointed. Until tomorrow they are having a 70% off sale on many of their courses.
A few I have heard and would recommend:
Modern Western Civ (I am doing this one now)
History of Ancient Rome (not rated as well on this site but this is probably my favorite)
I am kind of amazed how long the list is, but I have actually listened to several others I would not recommend or that are not on sale.
Update: Use coupon code VFRC to get an additional $20 if you spend over $50. By the way, I don't get any commissions. I just believe in the product.