I totally agree about the happiest baby book! Even if you don't have a really demanding baby, some of Dr Karp's advice and ideas in the book can still be incorporated piecemeal to make your life easier.
So far I haven't needed to use the full 5S's from the book on my 2-month old baby yet but by taking some of the book's suggestions on swaddling him tightly (the Miracle Blanket from Mothercare is a godsend!) and playing white noise (I use the BabyPlus - which is meant for prenatal dvpmt - but it's good for this as well!), these have really helped to extend his sleeping times (esp in the early evenings when he's fussy or late at night between nursings.)