http://www.kidsdiscover.com/
This catalog from KIDS DISCOVER Teachers catalog is from Discover magazine and is targeted for students ages 6-12. The catalog provides access to back issues of the magazine, teacher guides, etc.
http://www.tomsnyder.com
This is a catalog of K-12 educational software in all subjects from Tom Snyder Productions.
http://www.flinnsci.com
Flinn Chemical and Biological catalog and reference manual
http://www.freyscientific.com
Frey Scientific catalog of science supplies and equipment
http://www.eNASCO.com
NASCO Science catalog of supplies and equipment
http://daigger.com
Daigger Lab Supplies catalog.
http://www.deltaeducation.com
Delta Education catalog of science supplies, especially good for elementary science
http://www.epidisplays.com
Educational Products, Inc. science fair catalog
http://www.forestry-suppliers.com
Forestry Suppliers, Inc. catalog of great outdoor science supplies and equipment
http://www.carolina.com
Carolina Biological Supply catalog of science supplies and equipment. Carolina also offers kits for the GEMS curriculum, for the Science and Technology for Children (STC) program, and for the Science and Technology Concepts for Middle Schools (STC/MS) program.
http://www.lhsgems.org
Great Explorations in Math and Science (GEMS) catalog. From the Lawrence Hall of Science in Berkeley, CA. Provides lists of all their conceptual-based science curriculum guides K-12 plus information on their kits.
http://www.aimsedu.org
Activities Integrating Math and Science(AIMS) catalog. From the AIMS Education Foundation, this catalog lists hands-on curriculum materials and teacher guides for grades K-9.
http://www.sciencekit.com
Science Kit & Boreal Laboratories catalog of science supplies and equipment.
http://www.etacuisenaire.com
ETA Cuisenaire K-12 science catalog of supplies and equipment. ETA also offers a catalog of mathematics manipulatives.