People love to find out their family is a part of history. Make it easy and tell them!
The most exciting thing to my family and friends is hearing about the famous and historical people we're connected to. Geni has a great feature that attempts to find "How are you related?" to such people and the Top 100 is always an interesting place to start, but this needs to be taken a step further.
I'd like to see Geni make this more personal by providing members a list (ordered by direct ancestry and distance) of their connection to famous and historical figures. Since the trees are tied together, Geni is in a unique position to offer this feature to their users. It could use existing Geni projects as a basis for identifying prominent figures. My first entry would probably be Stephen Hopkins (Mayflower passenger and first mayor of Plymouth) as my 11th Great Grandfather, but I may be directly or closely related to many famous profiles, but I'd never know if I didn't research them myself or stumble upon them. Since Geni allows you to connect into an existing tree that someone else has researched, I may never realize a connection to a famous figure in the new tree.
I think a feature like this would really excite the general users of Geni connected into the big tree and perhaps encourage merging.
While we're waiting, I did create this application that uses the Geni API to do this to some degree: https://historylink.herokuapp.com