Receiving blankets are quick and easy to make, and the baby will need several, so that's a good choice. The easiest of course is to just get a length of flannel and turn under all the edges, and it's nice to have a few of these.
One style that has been really popular lately is the two-sided square version that has mitered corners. It's a bit more substantial than the one layer sheet version.
Nancy has sewn up a sample using flannel and minkee, so it is a bit of a cross between areceiving blanket and a quilt.
It is very soft and snuggly!
You can also make a lighter version by using a lighter cotton in place of the minke, or two pieces of flannel.