I can give some tips to you for helping and encouraging mom, but 2 questions first. Are you having the baby at home, at a hospital, or at a natural birthing center? Does she plan on nursing the baby?
Those questions aside, I agree with pp's that you are going to need rest. She is gonna need you strong and awake for the end. Make sure you have your bags packed. Have a note on top of the things that you can't pack yet, but need to bring. Things like cell phone chargers, camera, etc. I hope you have a good camera. I regret waiting till my daughter was 3 mos old to buy a good camera. You need a camera with no lag after you press the button before it takes a pic. Babies and small children don't pose!
Some good pics to take:
When wife goes into labor take the last "belly shot".
Take pic of wife in front of hospital/ birthing center sign going in (if applicable).
Ask permission to take pics of baby with the nurse, doctor, midwife, etc, (Be sure to write down their names).
Get a pic of baby with everyone that comes to visit.
Pic of baby ready to go home.
With my daughter, we picked a med sized stuffed animal and took a pic of her with it next to her when we first got home, at 2 weeks old, 1 month, 2 months, etc all the way up to 1 yr old to show how she had grown. These are some of my favorite pics of her
I also agree with pp's about putting guests to work. You are going to be exhausted. You are not there to entertain them. Don't feel you need to. If they can't understand that, they can leave. You have other things to worry about. When they call and say "can we come over?" Say, "great what are you bringing us for lunch/dinner?" While they are there don't be afraid to say "before you leave, would you mind washing a few dishes/ starting a load of laundry/ whatever you need done, before you leave?"
If you are home with mom and baby for awhile, sleep in shifts. When baby sleeps, you sleep. Make sure all your laundry is caught up before baby gets here. Do a load everyday if need be to make sure you don't get behind.
Lastly, you HAVE to stay encouraging. Be sure to remind your wife daily how beautiful she is and how much you love her. I hope she doesn't end up with PPD, but there is going to be some hormonal let down and it will probably mean some tears over things that you just don't get. Just be encouraging if this happens. (Poor dshai got a lot of this after we had our daughter.)