My kids lived in their Halo Sleep Sacks. They are normally about $20 each but on Woot, you can get them for $7.99 each (and you can get up to 3 at that price!) Plus they have $5 flat rate shipping!
These are great for baby showers for the new moms that don't yet know how wonderful they are. You can keep the baby warm without feeling guilty about using a blanket!