The leftover hexagons make great potholders! Stitch two together, with a layer of heat-resistant batting, add a hanger, and voila, instant potholder. Since I used different hexagons on each side, they're fun on the back and the front. I made a bunch of these and gave them as stocking stuffers to my family. Here's a picture of the one I kept. It was the first one, so I had no real idea what I was doing and forgot to add a hanger. It's now been well-used and is quite stained.
Here's the one I gave my mom. When I first called to ask her to take some pictures to send me, she got a little hysterical because she couldn't remember having seen it since I gave it to her for Christmas- she knew it wasn't in the potholder drawer and thought she might have thrown it away. Luckily, she had hung it on the wall next to the coffee pot to add a little color to the kitchen, and had just gotten so used to seeing it she forgot it was there.
This is a great thing to to with any leftover blocks that don't make it into the final quilt, and they make great gifts. The only thing I'd recommend is using two layers of the special heat resistant batting; I only used one and it's a little thin when you're holding onto something hot for an extended period.