Injinji
I have been a fan of Injinji socks for some time, and I always wear an Injinji liner sock with a Wrightsock over them. This is an awesome combination, as the Injinji protects the toes and the Wrightsock is double layer, giving me three layers to help prevent friction. The original Injinji liner was designed for hiking, so it was rather long and it was also a little coarse. Strangely, the liner sock was never shown on the Injinji web site, and the only place I could ever find them was Zombie Runner (my favorite running shop; they sell things you never knew existed).
Recently (July 2010) Injinji reintroduced the liner socks, so I ordered three pairs as soon as they came out. The updated liner is available in mini-crew, which is a much nicer length. The sock is stretchier, and before you put them on they look tiny. This gives a closer fit, especially around my toes, which are shorter than normal. The material and weave much softer, though the previous generation never caused me a problem.
Highly recommended - http://www.zombierunner.com/store/categories/clothing/socks/injinji/product2774.html