Wikipedia: List of sovereign states by current account balance

Surplus in Billion US-Dollar (2011)
Rank Country	  Surplus
1.   Saudi Arabia 252.756
2.   Germany	  219.938
3.   Russia	  198.760
4.   China	  155.142

Here's why neither the Ruble nor the Yuan can be reserve currencies: there just aren't enough Ruble- or Yuan-denominated assets going around to support it.

A society committed to the notion that government is always bad will have bad government. And it doesn't have to be that way. — Paul Krugman