As you may already know, florescent lamps use a small amount of the metal mercury to produce light, so being resposible citizens of our planet, we take our spent flourescent tubes and Compact Flourescent Lamps (CFLs) in for recycling, lest we be putting more mercury into our environment. Here is a good starting place to learn more about Lamp Recycling

They have a List of State Regulations and Contacts to research your home turf as well as Recycling Household Lamps