So I plan on starting my registry this weekend, and just wanted to share my experience using MyRegistry.com with you all.
I used this site for my wedding registry and it worked wonderfully. Once you sign up, you can install a button on your toolbar that enables you to add anything from any website to your registry. For example, I added an iPod speaker by going to Amazon, finding the one we liked, hitting the the 'Add to MyRegistry' button I installed, and it automatically added an image of the product, price, and link to buy to my registry. I liked that I could find the best price for the exact item I wanted, in turn saving money for friends and family.
We found it convenient that we didn't have to create one registry from one store and feel locked in to one retailer. I liked that you can even add experiences to the list. For example, I was able to register for a sky diving adventure! I may add some Zumba fitness classes... For postpartum use! You can even request cash gifts on your list, although I haven't done this, and attach a cute caption/photo (like LO's future college fund, etc).
I believe you are able to consolidate existing registries from all the big retailers like Target and Giggle into MyRegistry. There is even a phone app that allows you to scan barcodes for items in stores to add. I'm going to try that this weekend.
I included a link to my registry on my wedding website, and was able to see updates like with any other registry. We found it extremely cool to have everything we wanted in one registry website, and highly recommend.

Re: MyRegistry.com - baby registry for practically anything!