I have a lot of yarn. I like to make mittens. The combination works.
Here's what you can do with those sock yarn leftovers, or the single 50-g skein you found in the sale bin (or, mysteriously, unaccompanied in your house). By joining a strand of sock yarn with a strand of worsted, you get a slightly thicker yarn, slightly thicker mitten, and slightly faster knit -- and a mitten that is much more interesting.
My favorites so far are the bright blue with rainbow flecks over there on the right.
I am using my basic mitten pattern, available here. I follow the one that starts with a cast-on of 32 stitches and get a size that fits a medium-to-large large woman's hand. Use one needle size larger than you'd use if you were knitting with the worsted alone.