My sister-in-law loves socks. So does my older daughter. Socks are a fun gift - they're useful, but they can also hep the recipient really show off his or her personality in a quiet way.
I recently had the chance to try out some socks from The Sox Market, a marketplace that sells tons of different socks. There are some to fit every personality, male, female, and child. There are also socks appropriate for people with certain medical conditions (edema, diabetes, etc). The site is easy to search by theme, and also has a search bar if you want something more unique.
The pairs of socks I got to try were all different brands, but were cute, comfortable, and well-made. It's definitely a site I'll use for gifts for the sock lovers in my life!