I have to respectively disagree with most of you on this. Although Geni.com has been pushing collaboration and growing the Big Tree (and many of us support this attitude), I think there is absolutely nothing wrong with folks using this site to post their private tree - no matter how small or large. Even if these folks have no wish to grow their tree, Geni.com is still a very valuable way for them to show their tree to their own family members.
If you look back at various discussions over the years, you may find that this question had come up again and again.
I don't want to open up old wounds, but I feel I need to say something here, or else I would be tacitly agreeing with what everyone else is expressing.
Enjoy Geni.com, and make the use of it you wish, but please respect the desires of others - otherwise i fear that we may drive them out of Geni.com, and they have as much right to use this site as any of us.