There are a few free patterns out there, as well as published ones. Spin-Off had a "better mousetrap" sock a while back that was knit sideways in garter stitch, including the toe and heel in the sideways knitting.
Knitpicks has a garter stitch one where you add the toe on after knitting the leg, heel, and foot sideways, here.
Opal has one that also has an add-on toe, but in stockinette -- great for self-patterning yarn! That one is available here.
If you want traditional socks but with a sideways leg, Fiber Trends has a fun pattern called Ribs on the Side. The cuff is knit sideways, and the foot is knit "normally".
I knit the Fiber Trends one, the sideways rib was fun to do, and you can make the leg as long as you like, then knit the foot onto it. The leg is a knitted horizontal rib often called "Shaker Rib", if you like to make your own sock patterns.
(posted by me this day on spindlers)
