It's Our Tree is a genealogy service that lets people create very simple family trees using Adobe Flash. Like Geni (review) and Kindo (review), the idea is to get your entire family involved by inviting them to join and add family members they remember. It doesn't offer some advanced services like DNA sleuthing using cheek cells, but it's incredibly simple to get started, and the finished product can double as a Rolodex, birthday reminder, and private e-mail system for you and your family.
Like Geni and others, to get started you simply add family members using the directional arrows found on each person's block. There's support for divorces, first, second, and third marriages, half siblings, and any other oddly conceived (literally) member of your extended family. It also supports nine different languages, meaning if you're trying to share your tree with your Italian grandmother she'll be able to see it in her language, including the invite to participate. It's a nice touch if your family is spread out.
Each family member you (or others) create gets his or her own profile in case you feel like turning the service into an updatable family phone tree. My one irk with this is that they don't take advantage of a pre-existing contact-management service like Plaxo, Gmail's contact list, or LinkedIn to save you some time of having to dig all that up. What does make these profiles interesting is that you can add all sorts of geo-data to your family members including the place of birth, death, burial, and present location. This information can be toggled on a large Google map, which can lead to some really great exploration if you're willing to spend the time researching and inputting it all. Ancestry.com's DNA service will do something similar, although it actually shows you where your family is from based on cultural migration.
I'm giving this service a thumbs up, although if you're already tied to one of these services, its feature set is nearly identical to Geni and Kindo, so give it a look before trying to get your whole family to convert. Grandma will say grazie.