Mexico - riots last summer following increase in the price of maize flour.
Indonesia - mass protests this month when price of soybeans increased.
China - deadly stampede last November in western China in rush to buy subsidized cooking oil.
Russia - food price freeze preceded the parliamentary elections in December.
Burma - tens of thousands of monks and citizens took to the streets of Burma in September, partly in protest against rising food prices.
Source: Jami Miscik, head of global sovereign risk at Lehman Brothers, via FT. I added the last country, Burma, to the list.