Gem Collection at the Smithsonian - view diamonds, emeralds, rubies and sappphires http://www.mnh.si.edu/earth/text/2_1_3_0.html
Rocks for Kids - Names of rocks and their characteristics http://www.rocksforkids.com/RFK/TableofContents.html
Rocks - If you know the type of rock you have, there may be information about it here! http://www.ivyhall.district96.k12.il.us/4th/KKhp/RocksandMinerals/rocks.html
Here is an igneous rock site which also links you to sedimentary and metamorphic tours! http://seis.natsci.csulb.edu/basicgeo/IGNEOUS_TOUR.html
Rocks for Sale http://www.RockTumblingSupplies.com
Mamas Minerals - some samples for sale http://www.mamasminerals.com/page/MM/CTGY/RAMRUF