http://www.teacherspayteachers.com/ is a valuable website in which teachers can create an account and download lesson plans, activities, resources, printables, classroom posters and more. There are many resources that are FREE and there is also an option to purchase more if you would like to. I recently purchased a Science Unit on Position and Motion. I paid $1.99 for the entire unit. Talk about easy planning. Obviously i wont use everything in the unit and some things will need to be adapted but it makes planning so much easier.
Also, there is an option where you can add things to your wishlist for later on. There also is a feature that records what you have bought or downloaded for free. That way when can look back from year to year.
The search site is easy to use. You literally just post exactly what you are looking for and voila... done!
Check it out if you havn't yet! You won't be disapointed