I may have set the record for the longest time from cast-on to cast-off for a pair of socks. I finally finished the Jaywalkers I started last summer from the Vesper sock yarn I won in Claudia's MS raffle.
The only reason I got them done is that I had to sit through 12 hours of continuing education on Saturday, 8am to 8pm. You don't really have to pay attention (although I did; there've been changes I wanted to brush up on), you just have to sit there. The perfect opportunity to finish a pair of socks!