I was at my wit's end when my daughter turned 9 months old and was still not sleeping through the night. I wondered if I would ever sleep again! We finally started reading "Healthy Sleep Habits, Happy Child" by Dr. Marc Weisbluth. I swear, the first day we tried what he suggested, she started sleeping through the night. The big thing was that, as first time parents, we assume that the later you put the baby to bed, the later they'll get up (and it works with our schedule)... but the fact is, babies need lots of sleep and you have to make sure they're getting good naps too. Dr. Weisbluth say to put the baby to bed EARLIER because sleep begets sleep! We put her to bed a full 2 hours earlier than normal (around 530pm), and she slept for 12 HOURS that night! AND I was finally able to get more done around the house! You do also have to make sure he gets good naps too (45 minutes or more, two or three times a day). The better quality his naps are, the better he will sleep at night too.
We had a variety of things happen, though, where she would sleep through the night for a few weeks and then start waking in the middle of the night again... Routine would get messed up because of travel or whatever, she was sick and being congested woke her, or she was just overtired... so we'd have to go back to the book (we didn't read it all the way through--we're just reading it as she hits the new stage) and see if we need to adjust the schedule. At about 12 months, we had to start shooting for a later time--about 630 to 7pm--and she started sleeping through the night again. You're going to have to adjust a few times too, since they go through stages.
Dr. Weisbluth has done tons of research on sleep, and our pediatrician and a few peds nurses I know have all suggested this book.
We do not bathe our daughter every night, especially with the winter being harsh for the skin.
She also sleeps with a pacifier and a very soft stuffed animal. We only let her have these things for sleep, so she knows that once we hand these two things to her--it's time for sleep. Now, as soon as the binky is in her mouth and she is hugging her "bunny bear" (PJ Bear made by Ty), she puts her head right down and gets herself nice and comfy!
Oh, and the other thing that might have been a factor was that she might have been cold--not sure because we started putting her down earlier AND putting her in a sleep blanket at the same time (the sack that zippers and has holes cut out for arms and head). We have two Halo Sleep Sacks (you can find at Babies R Us); one is fleece for fall and winter, and the other is cotton for spring and summer.
Good luck! You WILL eventually be able to sleep again! :)