I'm a fellow insomniac, and I feel your pain. My doc thinks I'm bipolar, but whether that's accurate or not, I sometimes go for a month or more at a time without getting a whole lot of sleep. Do you have trouble falling asleep, or staying asleep? If it's falling asleep, sometimes what works for me is a seriously hot bath - I mean, very near scalding, but don't hurt yourself. Hot as you can stand. It relaxes your muscles. Be careful though - some people (diabetics, pregnant ladies) shouldn't take hot baths. Sometimes hot milk helps. What I really have to do during those times, also, is make sure I have a bedtime routine to shut down my day. Usually it involves a bath and a book. If nothing else works, I resort to sleep aids, too - my doc has me on atarax, but I hate taking meds so it's seriously a last resort.
Do you work out? I was told not to do my workout late in the day (apparently endorphins keep you awake?), so I do it in the morning, and I work the hell out of myself sometimes. 2-3 hour trail runs knock me out by seven pm. Sometimes that's just what it takes.
You know the other stuff - avoid caffeine, don't try to use alcohol (I used to do this. It puts you out to begin with, but I always would wake up around 2 am unable to go back to sleep. Besides, they say the sleep you get on alcohol isn't as good.), lay off the sugar, etc. Don't stay in bed when you can't sleep, get up. This supposedly helps you avoid associating bed with wakefulness. I gotta say, that's probably true for me - when the first thing you think about on looking at your bed is, "o God, am I going to have another night like that?", it's not real conducive to falling asleep.
If you're not sleeping well, make sure you take good care of yourself. Don't operate heavy machinery (seriously!) and be really careful when you drive. When I'm in a manic phase I don't feel tired, but I know that the lack of sleep affects my ability to think clearly. Hope this helps. Ask more questions.