Essays
Paul Graham on Startups - founder of Y Combinator
Idle Words - Intelligent thoughts.
Derek Sivers - The comments are interesting.
Aaron Swartz - founder of Reddit. RIP.
Skiing
Open Snow - Localized snow forecasts for a given mountain
Localized Ski Area Wind Speeds - lifts close a lot for wind.
Environmental Tech
Electrek.co
Infographics
How America Uses Its Land
U.S. Wind Map
General
Good list of science and social sciences blogs from Statmodeling
Other
History of American Education - on one page
High School Graduates Tables, 1869 through future
National Parks - from Google Arts & Culture
Learn
Excel