I have used Gems Opal merino wool which is very soft and also machine washable and dryable. I've used it for other projects besides socks as well.
http://www.louet.com/merino.htm
good luck!
Lynn
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FO tally since knitting odyssey began in Jan. '05:
5 baby blankets; 2 afghans; 1 large afghan for large brother-in-law; 4 scarves; 4 toddler sweaters; 6 simple teddy bears; This
teddy bear and 4 others from the book; 1 monkey; 1 tank top/cardigan set; 1 cape; 1 shrug; 1 pair mittens; 2 pairs socks; 2 pairs felted clogs; 1 hat;
lace edged tank,
Vitadini Lace Yoked Top
Currently working on: scarf for sis