Awesome Halloween costume ideas for toddlers?

I love Halloween! And the best part is making the costumes.

Last year, my son went as Frodo Baggins

I was really proud of that costume, but unfortunately it was so hot even at 8:00pm, that he was miserably uncomfortable, and ended up Trick-or-Treating in his diaper.

This year, I want to make him a great costume, but make it something he can have fun in.

I was thinking perhaps Conan the Barbarian?

Any other ideas?