As simple of an idea as it may seem, puzzles are often a forgotten "fun." Since Sweetie Pea was a tot, I have been picking board puzzles up at garage sales and thrift shops. I now have an entire drawer in one of my school cupboards/hutches filled with dozens of quality puzzles. The drawer is at tot-level and "open" to the public... meaning Greased Lightning and big brother Blonde Warrior...whenever they need some table time.
Here are a few more tot-friendly ideas.