I agree with all the above about Save Our Sleep. The routines are ridiculously rigid.

The Baby Whisperer I quite like, although I do take it with a grain of salt. Tracy Hogg seems to have a nice gentle approach in general, in that she stresses the importance of treating your baby with respect, which I really like. I found it impossible to follow her principles exactly, but I did get some very useful tips from her book.

But now I really want to try the other ones people have mentioned here!