After my post on Socks on 5th January, there have been quite a few comments about how to knit two socks at a time. I am feeling full of cold at the moment so I can't face making a tutorial myself, but I have put together some links to tutorials that may help if you feel like trying this technique.
KnitPicks has a good video tutorial on how to magic loop, shown below.
KnittingHelp.com is a great website for all knitting techniques. If you scroll down the page from the link you will find the video links for "Small Diameter" knitting, which shows how to knit Magic Loop and also how to knit with two circular needles.
Judy Becker's Tutorial shows how to cast on for toe up socks if you are doing two at a time on a single needle. Even if you only cast on for one sock it is still a useful technique for any toe up sock.
KnitPicks has a free pattern download for knitting two at a time socks. Please note I haven't tried this pattern and to be honest I've not even looked at it, but I thought I'd include it anyway.
Silver's Sock Class is the tutorial I used to learn how to do two at a time socks.
This video by Cat Bordhi, cuts off abruptly at the end, but before that happens you get a great tutorial (if fuzzy) on how to knit with two circular needles.
This tutorial from www.az.com seems quite clear for explaining how to knit in the round using two circulars.
CyberSocks has a 4 lesson tutorial on how to knit two socks at a time using 2 circular needles. (This is the next technique I want to try)
KnitAddicted has a PDF file to download which focuses on the gusset part of the sock knitted two at a time.
I hope these tutorials are an answer to some of your questions!
If anyone else has a favorite tutorial or knitting socks either using magic loop or two at a time, either toe up or cuff down, please let me know and I'll try to add it to this page, which will then be added to the Tutorials tab at the top of the blog.