Aish Hatorah
http://aish.com/holidays/Tu_BShvat/holiday_page.asp
JEWFAQ
http://www.jewfaq.org/holiday8.htm
Orthodox Union
http://www.ou.org/chagim/roshchodesh/shevat/tubshevat.htm
ORT
http://www.ort.org.il/year/2bshvat/
Keren Kayemet l’Yisrael
http://www.kkl.org.il/virtual_planting/default.htm
Medicinal Plants of the Holy Land
http://www.jajz-ed.org.il/festivls/tubish/medicine.html