NASA
Nasa: The Solar Wind
Describes solar winds, solar wind variations, and spacecraft studying solar wind. Also includes solar wind conditions for the past day/week.
Harvard University
Harvard University: The Sun
Includes a brief history of the sun's development and its future. Also provides simple statistics, solar activities, and references.
Other
The Virtual Sun: Between the Sun & Earth
The Virtual Sun by Michiel Berger provides a very brief overview of solar wind.