This is one of the little things I learned not long after I got married. Nathan's first action, upon coming home is to take his socks off...and leave them where he is standing. This was annoying, but I was willing to mostly let it go. I usually end up picking them up out of habit later in the evening.
What I noticed later on, and bothers me a bit more, is his absolute nonchalance about whose socks he is wearing. It wouldn't be such a big problem if his ankles and legs weren't at least twice as big as mine. He has worn out the elastic on many of my socks and I have recently threatened to have my sister embroider his name on all his socks. (By the way, in the picture, those are my socks.)
He says he does this because I put the socks in different drawers (which is true, they go where there is space for them) and he doesn't have time in the morning to fish his out, so he grabs what he can. To facilitate his wearing his own socks, I went through the two dressers in our bedroom, there is another in the computer room, but that is all his clothes anyway, and pulled his socks out, piling them on top. I hope this helps him find his own socks.