Some things I do with my dogs and puppies: 
* Schools at bell time.  Sit outside the gate and let the kids pat the puppy.  Doubles as a good way to teach children how to approach dogs.   
*  I always try and find fireworks.   I've even taken a litter of puppies to fireworks at six weeks of age (in a crate in the back of a car).    For my last litter our suburb was considerate enough to have them just a few streets away when they were seven weeks old.    
* A speedway or dirt bike competition.  Very loud, smelly and dirty.   
* Horses or stables if you know someone who owns one.  Get the dog used to being around horses.  Ditto for cats, chickens, cows, and other birds. 
* Markets with lots of people milling around and the dog has to calmly walk through the crowd at heel and not pull on the lead.