Socks are a great portable project, and they have long tracts of knitting (or crocheting) in which their maker doesn't have to pay too close attention to the project. Both features make the lowly sock a perennial favorite. However, their overall simplicity and the fact that you have to make two of them can lead to project boredom. Luckily, there are many, many different sock patterns available for different yarns, purposes, pattern stitches, and shapes.
Once one has made a few socks, it becomes fairly easy to free oneself from the pattern. The parts where one has to think (heel and toe) are proportional to the original cast on number and very predictable. Good thing, too, because what if you want to make a pair of women's socks from a man's sock pattern, or vice versa? What if you like the pattern stitch on a pair made from DK, but want to use it with fingering weight sock yarn?
I'm currently working on just such a project. I'm making a pair of socks for my husband, and I know from previous experience how many stitches around his socks need to be at the gauge I want to use. However, the pattern stitch I want is in this pattern (a lovely free pattern I found through Ravelry). It's for a different sized person and a different gauge. I also want to use a different kind of heel and include a short cuff at the top of the sock to give the top a more finished look. Since socks all follow a similar formula, it is very easy for me to take just the elements of the pattern that I like and apply them to my project.