Two months ago I was standing in Stockholm’s Stadshuset (City Hall). Soon, Thomas Sargent and Christopher Sims will be there as well. The pair, however, will be accepting the 2011 Nobel Prize in Economics.
Although I am not a macroeconomist myself, Marginal Revolution has a good description of the pair.
My old professor, Jim Hamilton of UCSD explains macroeconomic impulse response functions which Sims helped develop.