I know many moms replied who suggest the "cry-it-out" route - but you DO have other options if you don't want to do this method! There are LOTS of other, very effective approaches to improving sleep that don't involve looooooong bouts of your baby strongly crying, sweating, and eventually vomiting as he tries to settle (not much settling going on, eh?) to sleep! Please see below for links to websites and 2 books that all give you alternatives to "cry-it-out" and still help you both sleep more soundly.
I can tell you that for me, and for lots of other moms, we've found that the 1 yr mark is a time of *huge* transitions for babies (and so for us parents too)! There are LOTS of potential reasons that could all be going on at the same time for why he might not be sleeping well at this point: teething (often a big cause!), learning to walk/run (getting much more mobile), learning to talk, transitioning from 2 naps to 1 nap, eating more of and different varieties of solid foods (and possible upset tummy).
Also, based on your description of his having colic as a baby and never really sleeping well, I strongly encourage you to consider that he might react to cow's milk -- in fact, colic is a misdiagnosis in over 50% of cases (typically the real cause is food allergy and/or reflux or GERD). Sometimes the ONLY symptom of food allergy is poor sleep! If you want to find out whether he sleeps better without cow's milk, try a 2 week elimination of cow's milk (you'd want to read all labels and avoid any cow's milk and its derivatives like casein, whey, etc.) and monitor his sleep. If it improves, you pretty much have your answer. To be really sure, you could add cow's milk back in at the 2-week mark and watch for the sleep problems to come back. Anyway, here's what pediatrician Dr. Sears has to say about food allergies, if you're interested in exploring that more:
Tracking Down Food Allergies
http://askdrsears.com/html/4/t041800.asp
As far as sleep training, alternatives to "cry-it-out" (CIO), etc., I love these quick, practical, resources:
Quick and Dirty on Sleep
http://moxie.blogs.com/askmoxie/2005/12/quick_and_dirty.html
Babies and CIO (fussing vs all-out-bawling)
http://moxie.blogs.com/askmoxie/2006/06/babies_and_cio.html
Babies & Sleep Regressions
http://moxie.blogs.com/askmoxie/2006/02/qa_what_are_sle.html
And here are some books that you can typically get for free at your local library (longer to read than the quick links given above, but well worth it in my opinion!):
Good Night, Sleep Tight
http://www.thesleeplady.com/
No Cry Sleep Solution
http://www.pantley.com/elizabeth/books/0071381392.php
Also, depending on how mobile your little one is right now, I found that as soon as my babies were cruising and walking, they really *needed* a lot of opportunity for physical exercise during the day in order to sleep well at night - they were like energizer bunnies and really needed chances to climb, walk, squat, pull up, and just burn off energy in general. Days where they didn't get as much physical activity almost always led to a harder time going to sleep at nap or bedtime.
So... hang in there! Check out the resources available to you and decide what resonates with you most - you know your child and yourself better than anyone (any expert, any doctor, and any of us here on mamasource)!