Awesome Cleaning Slime am 1 tablespoons of white (Elmers) glue. Add about 1 spoon full of water. Mix. Then in another cup put 2 tablespoons of borax and 2 tablespoons of water. Pour the glue solution and the borax solution together and you get slime. Add some food color to the glue first if you want a cool color.
Just tried this on a small scale (3 x 5 ft) and it's already a ton of fun. Stick a small one in a shady spot on a hot day. The Water Blob tutorial: Amazing (and budget friendly) summer fun activity for all ages.