I've been reading a book I wish I'd had when my first child was born: "And Baby Makes Three," by John Gottman and Julie Schwarz Gottman. The authors write about how parents can keep their relationship strong as they adjust to the challenges of parenthood.
Most of the book is good solid advice on fighting well: remember you're on the same side, work things through, take a break when you need to. All of the conflict resolution skills you learn before you have kids but forget when you're sleep-deprived.
The Gottmans have an insightful chapter on parents' sex lives, too. What I found most interesting was that couples who adjusted well kept touching each other affectionately, even when their sex drives were low. Other "secrets of couples whose sex life is going well" include: accepting that things have changed, communicating, indulging in quickies, and making time for "gourmet sex."
To anyone who's had a baby in the past year or two - it's a challenging transition. Check out this book and see if it makes your life any easier.