In addition to the simple onesie every now and then in various shapes and designs (Q, Nebraska, turkey face), I tackled a car seat cover when the weather got cold. I think it turned out pretty cute!
I followed the tutorial found here. It was fairly simple and easy to follow. I found the monster fabric on super-sale a while back and have just held onto it while waiting for the perfect opportunity to use it. I bought the Minky lining on sale as well, so this whole project probably cost me $20 in supplies. I pretty much followed the instructions exactly, fitting it to my Britax car seat as needed. I added a little button on the front of the slit, snaps for the wrapped handle pieces, looped a small piece of elastic on the bottom sides near where the handle connects to hold the cover in place, and added 2 little bows on safety pins to hold up the front corners from brushing on the dirty ground when the car seat is set down.
Now Q has a stylish little cover to keep that cold Minnesota winter out!