A sure-fire winner for Pi Day (Mar 14): create Haiku poems about pi, called Pi-ku's. This is a great way to bring language arts, graphic arts, and mathematics together in one place!
A useful and fun set of cross-curriculum photo slide shows for maths, English, science, history and more. They are arranged by age and range from kindergarten Secondary school. A great resource for introducing topics.
http://ictmagic.wikispaces.com/Video%2C+animation%2C+film+%26+Webcams
In these last days of April, I wanted to acknowledge the yin and yang that this month represents for my discipline. April is National Poetry Month, but it is also the time of year when students in grades 3-8 take their ELA and math New York State exams. The irony of this is not lost on us English teachers.