I use them for smaller projects or for piecing. There is a shooting star pattern you can use the muslin as the center square and use little scraps from other projects to make the tips of the shooting star. Really cute!
http://www.quilterscache.com/S/ShootingStarBlock.html
http://www.quilterscache.com/S/Shoot...ock_Page2.html
I use Moda muslin so it is nice for piecing too.