http://scholar.google.com
http://books.google.com
http://academic.research.microsoft.com
http://worldwidescience.org
http://www.science.gov
http://www.refseek.com
http://www.virtuallrc.com
http://education.iseek.com/iseek/homepage
http://www.base-search.net
http://www.infotopia.info
http://thefree3dmodels.com/
http://www.creativecrash.com/
http://archive3d.net/
http://www.turbosquid.com/Search/3D-Models/free
http://www.blender-models.com/
http://www.blendswap.com/
http://katorlegaz.com/3d_models/index.php
http://opengameart.org/
http://freegamearts.tuxfamily.org/
http://freetems.net/
http://art.devsader.com/
http://hasgraphics.com/
http://www.derekyu.com/tigs/assemblee/
http://untamed.wild-refuge.net/rmxpresources.php?characters
http://www.lostgarden.com/search/label/free%20game%20graphics
http://texturelib.com/
http://www.ambardia.com/FreeGraphics/FreeGraphics.html
http://www.spriters-resource.com/
http://www.freesound.org/
http://www.soundjay.com/
http://www.pacdv.com/sounds/
http://www.nosoapradio.us/
http://www.jamendo.com/en/
http://www.vgmusic.com/
http://publicdomain4u.com/
http://simplythebest.net/sounds/
http://search.creativecommons.org/
http://www.blender.org/education-help/
http://unity3d.com/asset-store/
And of course.....
www.google.com