- Video cameras are nice, but get a microphone. If you have an iPod, get a microphone that attaches to it (iMic or something similar). Record your kid's voice (even the cries of the first few months) at least once a month, more if you can. You'll cherish these memories.
- When your wife breast-feeds, sit next to her when you can. Do not read a magazine, stare at the tv, or listen to music on headphones. Be there. Listen to the sounds. Watch your baby. This time doesn't last long, and it's really a miraculous thing. Be a part of it.
- Also, when wife is breast-feeding, offer stuff. Water. A pillow. The tv remote control.
- Get your muscles in good shape - not ripped, but just fit. Look for some easy stretching and toning exercises you can do at home. Once the baby comes, the trips to the gym are going to disappear, and meanwhile, you'll have more strain to your back and your legs than you can even imagine. And your shoulders. And your arms! Holy cripes, I couldn't believe how badly my forearms hurt sometimes, after rocking the kid to sleep for an hour.
- Stop cursing now. Listen to what you say. Start making yourself say "darn" or "fudge" or, I don't know, "hootenanny" - whatever else you can say besides actual curse words. I constantly curse when I'm in the car, driving, and I had to work to force myself to stop once I wasn't the only one in the car anymore. It's hard - start working on it now.
- Get a bunch of music you love (and audiobooks, if you're into them) and put it on your computer or on an iPod, something you can access quickly. If you're home at all with your kid, you'll have lots of down time where the kid's napping and you're stuck holding him/her.
- Don't use your wife's flouncy diaper bags with the really cute flower pattern. Buy your own. Whether it's an official dad diaper bag or just an old Jansport backpack, you need your own. Seriously.
- Don't let your wife go to ped appointments alone. You're part of this, too. Go. Have at least one question to ask at every appointment. If you need to, check with your wife for a good question.
- Last and possibly most important: take time for yourself. Dad work is important work, but take one day a month and go out for beers with your friends. Go watch a movie. Go to the ball game by yourself. Do the things you enjoy. Make proper arrangements with your other half, plan well in advance, and don't feel guilty while you're gone. (But you'll probably want to bring your cell phone, just in case.)
Go look at DaddyTypes to see the whole list of comments. The suggestions are all brilliant and worthwhile. It's an impressive showing of collective daddy wisdom.