Chabad http://www.his.com/~chabad/tu/
Dr. Nurit Reshef
Jewish Outreach Initiative http://www.joi.org/joiscripts/dgssearch/search.php?q=Tu+&r=10
JTSA Kid's Corner http://www.learn.jtsa.edu/topics/kids/together/tubshevat/
Ohr Someyach
Orthodox Union http://www.ou.org/chagim/roshchodesh/shevat/tubshevat.htm
SusieQ Tu B'Shvat
Torah.org http://www.torah.org/learning/yomtov/tubshvat.htm
Torahtots http://www.torahtots.com/holidays/tubshvat/tubshvat.htm