While most of these sites were not designed specifically for SMART Boards, they work well on the boards because they are interactive. Just use your finger to navigate the sites!

Comprehensive Listings

Lee Summit's List of Sites from district in Missouri
Center District's List of Sites from district in Missouri
Marilyn Western's Resources SMART-friendly sites marked with yellow box
Sheppard Software educational games and activities (mostly elem)
Topmarks content area activities, from the UK
Edhead Games
Invention at Play Smithsonian exhibit interactives on inventing
Dare to Compare quiz questions for 4th, 8th, 12th geography; 4th, 8th civics; 4th, 8th, 12th history; 12th economics; 4th, 8th, 12th math
Scholastic's Whiteboard Activities nice selection, all grades
Birmingham Grid for Learning 

Grade/Content Specific

Language Arts
Spelling City
My Storybook Maker from Carnegie Library
Mrs. P's Magic Library

Science
Universcale
Planets
FreezeRay's Science secondary

Social Studies
US Trivia Game

Math
Time for Time for learning to tell time

Early Elementary (multiple content areas)
Great Sites for Using the SMART Board K-3
Learning Planet
4Kids
FunBrain
Starfall Learn to Read
Starfish Theater
PBS Kids
Rolie Polie Olie
Sesame Street
Seussville

Music
Virtual Keyboard 
San Francisco Symphony for Kids
PBS Thumb Piano record and playback music, elem
Compose Your Own Music
Sphinx Kids Classical Music
Note Names spell words with music notes

Utilities

Online Stopwatch large, with sound, counts up or down

Just for Fun (maybe not so educational)

Singing Horses
Line Rider  fun!
This is Sand
Jigsaw Planet