J.H.
I have used the Baby Whisperer method for both of my kids (still working through it a bit with my 6 month old but he's catching on!). It inovlves letting them cry but only for shorter periods of time. I can't remember the exact method but it's basically where you let them cry for 30 seconds and then go in there and soothe them without picking them up. Then you walk out (or at least get out of their sight - I sometimes sit on my son's floor so he can't see me) and if they start crying again, let it go for 60 seconds then go back in and soothe the baby again without picking him or her up - try rubbing the belly or giving them a pacifier and holding their hand for a little while gently whispering something like "it's OK, mommy's here, it's time to go to sleep now" - I know it sounds silly to say that to a baby but it seems to work! Each time you have to go back in, wait an additional 30 seconds (so wait 30 seconds the first time, 60 seconds the 2nd time, then 90 seconds, etc). But this only works if you put them to bed before they are overly tired (you don't want to try this with a screaming, out of control tired child). With an older child, you may have to go back in quite a few times but (at least for me) the effort is worth the results! I've only had to do this a handful of times and my son seems to be learning to self-soothe. It does involve letting them cry some but not for extensive periods of time.