I spend most of my day playing but these are good activities! 30 for 30 Challenge: 30 Minutes of Playing WITH Your Kids for 30 Days! (This site has a lot of activity ideas for this challenge. starting as young as infant and up)
Make your own Sponge Water Bombs (alternative to water balloons). Cut sponges in strips crosswise, then stack 4 wide, 2 deep and tie very securely in middle with fishing line. Soak, play, have sponge water fight!