I started two books in 2010 that didn't get finished reading:
Rief Larson - Selected Works of TS Spivet
Mary Lovell - The Mitford Girls
I don't really know why either of these didn't make it to completion: the Spivet books is a visual treat and has a wonderfully strange narrative (I think it got lost under the bed for a while when I ran out of energy for reading in bed at night). Similarly, what is not to love about reading about the Mitford sisters?! A family whose biography must surely be in the televisual works for when Debo finally passes from this mortal coil - especially given the current passion for all things Downton/Upstairs etc... I have started this Mitford book twice, though the second attempt was only JUST before new year's eve so that maybe doesn't count.
Still: definitely two to make it through this year.