...no, this isn't an ad for Doublemint gum, but one could chew some while sewing with a double needle.
Made a few last minute Christmas gifts - fleece scarves. After sewing two 10" strips of fleece together lengthwise, I turned them right side out and did some top stitching. Had always wanted to try using the double needle that came with my machine, and really liked the results.
Corners were a little tricky since you can't pivot in needle-down mode, as you would with a single needle. So I raised the needles, rotated the scarf, and then hand cranked the needles down toward the fabric, making sure they lined up with the previous stitching before piercing the fabric. Seemed to do the trick.
If making the scarf for an adult, I use 5/8 yard. You could probably get away with 1/2 yard if making the scarf for a child. At Hancock Fabrics, even remnants that were $12.99/yd originally, sell for 3 bucks. I bought some extra fleece to make scarves for next fall's craft fair. :)