New kids’-activity site Kiddley wins my affection with a list of free or cheap activities for vehicle-obsessed toddlers. My son definitely falls into this category, and we have in fact done all of the activities mentioned.
I’ll add one more activity to their list: visit a local fire house. Most firefighters I’ve met seem more than willing to show a toddler around, and they usually manage to come up with plastic fire hats and fire-safety coloring books.