Best of the best

I am trying to create a list that will be useful to educators all over the country. Please list any great educators that consistently provide valuable information to be used in the elementary classroom and feel free to comment on why you feel that they are so great. Many teachers feel as I did just a couple of weeks ago- that Twitter is useless. I have been proven wrong and I would like to share this information with as many teachers as I can. Thank you for your help!