I'm planning a Batman Lego party for my DS. I got some sealed minifigures on ebay much cheaper than in store (second hand but still sealed). I'll be using them as party favours or prizes instead of lollies. I have been spending lots of time on pinterest! Lots of great ideas on there.

Some things I'm thinking of - printing batman lego pics off the internet, laminating them and hiding them around the yard for a treasure hunt. Kids can keep the pictures. Maybe give minifigures as a prize. I'm also thinking of using an internet pic for the invites and doing something up at home.

Slip & slide & paddle pool just because it's summer lol.

Lots of bright primary colours for decorations as someone's already mentioned.