Petition against Monsanto's GE Alfalfa: 

http://www.change.org/foodandwaterwatch/petitions/view/ask_president_obama_to_protect_organic_and_stop_monsantos_ge_alfalfa

Anyone and everyone can send comments to USDA on regulation decision for one particular genetically modified corn:

http://www.aphis.usda.gov/newsroom/2011/01/ge_corn.shtml