No matter what you teach, if you are looking for a lesson or a unit for a particular concept, chances are Curriki will have something you can use.
Curriki is a collaborative website containing tons of curriculum for math, language arts, science, and social studies.
If you're a giver, you can contribute lessons or units you've created to Curriki. The site definitely depends on the givers out there to amass the wealth of resources they have.
If you're more of a taker, you'll find plenty of good quality lessons and units here. I used parts of several units from Curriki this year for some history lessons on the spread of Islam. I was able to download the background info I needed to teach some lessons, and also some great individualized projects to go with it that were created by a contributing teacher. They were so good I wrote him a thank-you note/comment on the site!
If you're both a giver and a taker, then you'll love the collaboration aspect of this site. It's possible for you to work with one or more teachers in your content area to contribute materials and create a joint lesson or unit!
Becoming a member of Curriki is simple - just the usual name and email information. I can tell you from personal experience they almost never bug you with info or updates. I've gotten maybe 2 emails from them since I first joined last August.
I can tell you that the site is really easy to navigate, and more new materials are added all the time!