A while back we took our little guy to the local parents-as-teachers "messy play date" event for preschoolers. They had set up all kinds of play tables full of toddler-appealing things to touch and feel, such as...

wet, gooey spaghetti noodles...a pool full of shredded paper...
a tub of green slime...
Jello!
potato flakes and sand toys...
He had a great time and the really fun part is that if we ever get bored at home we can recreate some of this pretty easily and have our own messy playtime in the kitchen floor.