Here are some great sites with projects and activities specifically for babies, toddlers and pre-schoolers. All these sites are fun to visit either with your kids or by yourself for lots of new ideas.
Crayola--Free coloring pages, crafts, lesson plans, games and more.
iknowthat.com--Online, multimedia, educational games for PreK through 6th grade.
Fisher Price--Games and activities for infants, toddlers, and pre-school age children.
Kids @ Random--This site from Random House gives access to mini-sites for favorite characters from Disney, Sesame Street, Nickelodeon and more. Mini-sites have information, games and activities.

KneeBouncers--A collection of silly games just right for toddlers.
Nick Jr.--Games, video, and project ideas from Nick Jr. shows like Dora the Explorer.
PBS Kids--Coloring, games, videos and music from PBS Kids shows.
Sesame Street--Games, videos, and information on everyone's favorite muppets.
UpToTen--Games and on-line activities for children up to 10 years old. Everything is available in both English and French.