I did a bookcase quilt for my SIL filled with baby toys and books. It was alot of work but so much fun to put together and can be personalized to your sister.
Here is a link to the pix:
http://www.quiltingboard.com/t-136698-1.htm
My SIL also picked fabric that worked with her theme and I used it to make a quilt for her. Then I bought solid colored sheets/bumper/crib skirt that coordinated with the quilt.