IPEVO Document Camera

This is not free, and some might say that $65 isn't exactly cheap when it comes out of your own pocket, but this piece of equipment has more than paid for itself in the short amount of time I've owned it. 
http://www.ipevo.com/prods/Point-2-View-USB-Camera/IPEVO

Here are some ways I've used it to save time, and ultimately, money:

1. Use it to project a book you'd like to read as a class, but don't have enough copies of the book for each student.  I use the Interactive White Board to highlight and discuss the book as well.  Sometimes I only have one copy of a chapter book, but this allows the kids to have a "printed copy" in front of them.
2. If you have a copy limit at your school like we do, then you'll love this one.  For morning work, I often have the students complete part of a math worksheet.  Instead of copying a worksheet for each student in the class, I print one copy and put it under the document camera.  The students copy the math problems and complete them on notebook paper.
3. You click the button on top of the camera to snap a picture of whatever is below it.  This can be great for science experiments.  I recently constructed a parallel and series circuit under the document camera (live action while the kids watched) and then snapped a pic of it.  I then saved the file and was able to use that same file for several days while we explored and discussed circuits.

See Ladybug's blog for the way she uses it:
http://ladybugsteacherfiles.blogspot.com/2011/10/cheap-document-camera-ipevo.html

Also, this is a great website that gives tons of ideas on how to use document cameras.  It's divided by grade level so you can choose the activities that best fit your classroom:
http://www.edtechnetwork.com/document_cameras.html