To turn an old t-shirt sleeve into a baby hat takes about a minute--or less--using Jill's technique. Basically you hem the widest part of a long sleeve with a zig-zag stitch so it stretches, and then finish the top any way you like. Personally, I think the bunny ear version is marvelous!!
Jill also notes that using a short t-shirt sleeve is even easier as you don't have to hem the bottom--in this case, the widest part. Clever!!