At a recent class I attended with other soon to be parents there was lots of discussion about registering for baby gear; where to do it, what to register for and what people seem to want to buy you (this if often what is not on your list).
A lot of moms I have talked to are registered with Amazon so that they can get a variety of different items and brands all in one registry rather than having to go multiple places, like Babys-r-us and Target, to accomplish this. My one issue with Amazon is the shipping cost and time. If you are getting something that say you end up not needing or for some reason receive multiples of you will need to do a return, which can be a hassle. Plus, I know a lot of grandparents, aunts and uncles want to touch, see, feel what they are purchasing and an online purchase just feels so impersonal.
One very neat website that was mentioned by a fellow classmate is http://www.myregistry.com/ which allows you to pull all of your registries together in one location. I love this idea, which gives you the flexibility to register in multiple stores but to provide one link to family and friends to eliminate confusion. Someone can go shop in-store with a printed copy of your registry in hand if that is how the prefer to shop. Of course, they can also shop online as well. This site can also be used for birthdays and wedding showers!
Once you figure out where to register then you have the dilemma of figuring out what in the world to register for. I have looked at so many suggested registries from different forums, blogs, businesses, birthing class lists, etc. My favorite so far was found at Rookie Moms: http://www.rookiemoms.com/shopping-registry/ This is what I am using to help me complete my registry and to create my checklist. I love how the break down their list into different categories so you can think about what you really need, what you will get lots of use out of it and then the stuff that would be nice to receive but not a necessity.