decorated sneakers
Decorated sneakers. There is no link for this one but the photo is really all you need. Just give the kids a new (cheap!) white pair of sneakers and let them use Sharpies to decorate them. This definitely works best for older kids but you could draw simple designs in black Sharpie for younger kids and have them color them in.
Absorbing Artwork. Some glue, card stock, salt and colored water are all you need to create these pretty dimensional works of art. To keep them busy longer (and for a wonderful work of art) buy a larger canvas and have several kids work together.
http://thatswhatwesaid.net/2011/11/absorbing-artwork/
Beaded Frame. Pick up some inexpensive wood frames at Michael's and a few packets of beads. Let the kids cover the frame completely with glued on beads. Older kids will enjoy creating patterns while the younger ones will have fun just randomly putting on beads. Print out a picture of the kids making their treasures and put in the frame for a great keepsake of a fun afternoon.
http://www.familycorner.com/crafts-kids-family-2/make-a-beaded-frame-for-mom.html
Homemade Bath Paint. You read that right--homemade bath paint! Body wash, cornstarch and food color combine to create bath time fun. Have the kids mix the ingredients and then toss them in the tub! There are other fun ideas for rainy day crafts on this site. http://www.parentmap.com/article/10-rainy-day-crafts-and-activities-for-kids?page=7
Rainy Day Splatter Painting with a Toothbrush. For younger ones, cut out the umbrella shapes and help them glue down onto the card stock. Older kids will be able to create their own background. Then, just splatter on the "raindrops."
http://www.flipflopsandapplesauce.com/2009/03/rainy-day-splatter-painting-with.html