Read.
I've GOT to read. I've been known to read totally lame things like Army training manuals, or super old magazines or month old TV Guides. No lie. It's darn near sad how hard it is for me to go to sleep without reading.
The good thing is that I almost without fail I read for at least an hour (usually two) each day. The bad thing is that it keeps me up later than is best for my sleep needs.
Also, I have a hard time reading while sitting up. Yes, I know, I'm weird. But I'm me. :)