Play Simon Says, redux. Put a twist on the game with Spider-Man Says -- or whoever's popular in the house that week -- and everyone can take turns being their favorite superhero. Mix it up every time: "Spider-Man says, 'Pretend to spray a web on the wall!'"
Go on a free field trip to the pet store. It's too cold for the zoo; spend an hour checking out the cute puppies and kittens. If your kid's really into wild things, look for a store with exotic creatures.
Try a valentine craft. Trace and cut out a big heart shape from a brown paper bag. Little kids can crush or crinkle small squares of red and pink tissue paper into balls; older kids (or you) can help them glue the tissue balls on to cover the cutout or arrange them in the shape of the letters "D-A-D."
Jazz up "Head, Shoulders, Knees, and Toes". Keep a pack of stickers in your purse; when your toddler's getting antsy in a restaurant, stick them all over her body. Sing the song, then ask her to find them, and name the body part each sticker is on together.
Visit this cool site: Soapbubbler.com It's got tons of cool videos of soap-bubble artists making colorful creations out of soap and wands. The gently transforming bubbles will have everyone mesmerized.
Revisit Red Light, Green Light -- indoors. Forgot how to play it? One person is the "stoplight"; the rest of you form a line several yards away. The stoplight turns his back to you and yells "green light!" You all run toward him until he yells "red light!" and turns around. Anyone he catches moving is out. The game's over when someone tags the stoplight or everyone is out.