Games for 3yo birthday party

[Astrid]

Bubble machine. Keeps them amused for ages

[CC11]

Pin the tail on the donkey (or whatever your theme is, I am doing pin the heart on the cupid for a valentine's day themed party)
Treasure hunts of any kind -I am hiding paper hearts
Pinatas
I am filling a bowl with candy hearts and giving the kids chopsticks (or spoons for younger ones) to see how many they can transfer to their own bowl in 60 seconds

I am also printing out some colouring pages from the web, mazes, join-the-dots etc and supplying crayons etc that they can do sitting at a table

I could think of some more but DD is waking up from her nap!