Originally Posted by arctos

I have used Smartwool merino wool socks for the last five years with good results.

An alternative is by DeFeet designed for biking. I have used two pairs for the last year and like them very much. The thickest one is called the Woolie Boolie and is 64% merino wool, 34% Nylon, 1% Lycra. The thinner one is called the Wooleator. It is 63% merino wool, 26% Nylon, 10% Cordura, 1% Lycra.

Just yesterday for Christmas I received a pair of bike socks from Icebreaker. Mostly merino wool with a nice fit.