This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
Well ok, but you seemed to miss the point of my post.
There are great libraries (no where as good as java) but you can dynamically extend them. Like (what should be) BigIntiger - you want to make a return of a long or even better BigInteger - you can in python on the fly.