Pattern: Gusset-Heel Gansey Sock (free, .pdf), by Katherine Misegades. Misegades has also written a useful Sock Workshop which goes through the entire pattern, step-by-step, explaining and illustrating the how-to of every detail. Every element of the sock is based on traditional ganseys (the heel, for instance, is half of an underarm gusset) ... if you're considering knitting one of these sweaters, this sock is an ideal technique trial run. I also think it's a good beginner sock ... every stitch charted and explained, larger size yarn and needles for visible progress and getting to triumphantly finish and wear them soon, very easy heel construction and turn.
Yarn: Tanis Fiber Arts Yellow Label DK in "Jewel" colourway. My top photo is the most colour-true (on my monitor, anyway). Lovely yarn to work with and to wear. Although the parameters of the yarn are virtually identical to the Regia 6-ply I've previously knitted this pattern in, the socks feel a little short ... they fit, but have to work at it. I may undo the toe graft and Russian join my leftover yarn to knit a couple extra rounds to extend the foot ... will see how they are after laundering and a touch of wetblocking first.
Needles and technique: Knitted two-at-a-time on two Addi Turbo 2.5 mm circular needles. Pattern uses knitting through back of stitch for fake seam, knitting in stitch below (both right- and left-leaning) for heel increases, slip-slip-knit, purl two together, and knit two together for heel turning and toe decreases. Pattern stitches are all simple knit/purl combinations
Ravelry Project Page