All you need to make any rainy day tons of fun:

Tin Can robot making kit    

Qwirkle Board Game    

Sculpey clay  

Smores

Bellz (fun, magnetic game)   

Mad Libs   

Sleeping Queens card game  

Organic Popping Kernels

Doodle books  

Eco Crafts by Alex Toys  

Twister Board Game  

Bottle of Red Wine    

Wood Birdhouse for painting    

Anatomy model kit    

Minions Coloring book