I have really found a goldmine of good links from the blogosphere this week. Check them out!
scribbit.blogspot.com is a wonderful blog with lots of fun activities such as:
The flour game
How to make a cheap mini pool table
Packing peanut art
Color-coded nature walks- love this one!
Ping-pong power ball
Berlin's Whimsy has a creative list of children's activities. My favorite is "Picnic around the world"
Vanilla Joy has a cute family game that would be fun for little kids called "Don't Eat Pete!"
Growing Great Kids has a terrific idea for painting with magnets
Toddler Learning Activities is a blog devoted entirely to toddler fun!
Have any more to add that you've found? Let me know!