I haven't found another online registry tool with its capability. Here's how it works: create an event and invite others to join. Everyone creates a wish list and purchases gifts for others by viewing their registries and what others have purchased for them. You can have multiple events and a different list of members for each one. Plus, if you dare to go "off registry" for someone, you can add that gift to their profile just in case someone else was thinking the same thing. In the end, everyone's happy. This year, it will be extremely helpful for me since my wish list will include many handmade gifts from Etsy, which can be difficult to communicate to those who aren't familiar with the Etsy world.
Not convinced one way or the other? You can view a demo of the tool on the website.
Bottom line: It's simple, extremely useful, and you aren't bogged down by advertisements.
Tell us, have you tried CheckedTwice or another online group-style gift registry for assistance during the holidays?