Virtual rock collections:
http://comp.uark.edu/~sboss/vrockbag.htm

These folks used egg cartons to collect and mark their rocks!: http://www.mngs.umn.edu/virt_egg/secondpg.htm

http://www.dcnr.state.pa.us/topogeo/collecting/index.aspx

Saw that this pointed out some good dig sites if you wanted to go gather some specimens:
http://www.pennminerals.com/collecting.htm

This is like a PA virtual rock collection. I thought it was neat because it shows the rocks found in this state.
http://www.rockandmineral.org/history.htm

Fossweb: http://www.fossweb.com/modulesK-2/PebblesSandandSilt/index.html

How Rocks are formed: http://fi.edu/fellows/fellow1/rocks/create/index.html

This planet Rocks: http://library.thinkquest.org/J002289/

Rockhounds http://www.rockhoundkids.com/index.html

Identify Rocks Game (took a while to come up) http://www.kidsgeo.com/geology-games/rocks-game.php

Virtual Rock lesson http://www.learner.org/interactives/rockcycle/