Connie asked about the pattern I follow for baby socks, and rather than bury my reply in the comments, I thought it would be more useful to answer right here, out in the open.
I follow a very basic sock recipe, similar to the one written out by sock-knitter champ Susan Anderson here. For an infant or baby size (up to 1 year), using sock yarn or weight-fingering yarn, I cast on 40 stitches.
A stretchy cast on is essential as babies have sensitive little legs; after hearing that my lovingly-crafted baby socks didn't fit my baby granddaughter as well as I had hoped, I researched this topic extensively (once a grad student, always a grad student) and found very little about it in the sock-knitting books and and articles which I was able to find, at least when it comes to knitting from the leg down. I tried various methods without much success. Ultimately, I settled on a method demonstrated by Ann Budd in the companion DVD to her Sock Knitting Master Class book. She recommends a standard long-tail cast on, with a gentle stretch of the barely formed stitches every 4 stitches or so. This way allows for a bit more yarn than usual in between the cast-on stitches, which in turn results in a slightly more stretchy edge.
Afterwards I proceed as for a regular, adult-size sock; if you are concerned about socks staying on (always an issue with baby feet), then a 2/2 ribbing all along the sock, possibly with a wide cuff, is a good idea. I also like a 3/1 ribbing pattern, just because it has a nice working rhythm to it, but I don't know that it stays on any better than plain stockinette.
I knit the heel cuff back and forth on 20 stitches; on some baby socks I just use regular stockinette since babies don't need a reinforced heel. It's entirely up to you. I have also seen baby socks knitted with a garter stitch heel, which looked quite attractive. I like to pick up 11 stitches after turning the heel: 10 stitches for the instep and one extra stitch just to close up any hole that might appear. I learned this from Charlene Schurch's "Sensational Knitted Socks" book, but again, it's entirely optional.
As to the final length of the socks, I must confess I don't have a very good system. I borrow guidelines from online patterns. The craft yarn council offers this very basic chart. The Craftsy blog has this free pattern designed for newborns . Finally Connie mentions this pattern by Judy Ellis, which seems quite useful for our purposes.
If you are knitting for afghans for Afghans, I recommend not making the absolute smallest size. It's nice to be able to ship socks that will fit a baby beyond the first month of life, and the maternity hospital in Kabul doesn't need preemie size items. Keep in mind that the a4A volunteers work hard to pack and ship the items requested by their partner NGO in Afghanistan and that every bit of space in these shipments counts, which means that something that is too small to be of use will not be sent. Tiny infant socks may be adorable, but I would save them for a cute gift or keepsake for a new mother of my acquaintance instead. My feeling about size is that a 40 stitch-circumference will fit a baby through the first year of life, and that all a knitter needs to do is to vary the number of rounds between instep and toes... and to remember to knit a second sock that matches the first one.