I'd suggest asking for minimal clothes on your registry... people tend to buy clothing that isn't even on your registry, in addition to what you do put on it, so you end up with a TON of clothes, much of which you end up returning or not using anyhow. I'd suggest registering for all your "necessities" like your bottles, carseat, stroller, pack-n-play, towels, bath accessories, that sort of stuff, and use the gift cards or monetary gifts you get to do some gender specific clothes shopping after the baby comes.
As for carseats and strollers, crib bedding, etc., you can really get some nice gender-neutral stuff. There are some really nice patterns out there that could be used for either boys or girls. You'll just have to look around to see what you like. Personally, I got the whole way-too-expensive crib bedding set and all the matching accessories in a Noah's Ark theme for my son's room, and found it was such a waste. It really is purely decorative. When we moved out of my son's father's house, we left his Noah's stuff for him to have there, and I got a super-soft fleece-like bumper pad, a matching super-soft blanket, and crib sheet, all in a solid green, and I loved it so much more than the fancy-shmancy bedding ensemble that I just had to have. lol It was just so soft and cozy for my son, and that was what I loved so much about it. Plus, it looked clean, and uncluttered. And if you go with plain bedding like I did, it allows you to do anything you want in the room.
As for room color, I've always liked yellow. My son's room is yellow. It's just so bright and cheery, and can be accented with so many different options for either boys or girls. We did sesame street, which in and of itself is gender neutral, but its so kid-friendly, and bright cheery colored. I also love light lime green walls for boys or girls. You really do have many options. One last thing I wanted to mention if you hadn't already thought of this... today is the day of vinyl wall decals, and there are just a million of them out there. I'd definitely consider using those for decorating your child's room. They are so easy to place, move, and remove! Then you could even wait until the baby's here to choose and put the decals up because they are so easy. Not like putting up a wallpaper border or something that you'd want to have done ahead of time. Then you could do something in the room that's a little more gender specific, if you want. Just go with a neutral wall color, and get the decals after the baby is born! There are also websites online where you can buy vinyl decal words, phrases, names, all personalized. That would also be a nice, easy way to decorate the room. And the best thing about the decals is that in a couple years, when you child is a little older, you can EASILY change the whole room's theme by changing some decals!
Good luck to you! This is such a fun time.