We definitely need a category for Umbrella Projects. See for instance Randy Stebbing's recent post at http://www.geni.com/discussions/84186?msg=794839. Some of the most amazing project work on Geni is overlooked or understated. The three projects that come to mind immediately are the New Amsterdam, the Mormon Families and the Great Migration. Great work by Erica Howton, George J. Homs, Randy Stebbing and others working with them.
Also, I'd like to recognize those who contribute ground-breaking work in developing standards, such as the Naming Conventions project(s) and projects that Private User has created with lovely templates.
What about Best Of for the most engaging projects, where I would nominate projects that Malka Mysels, Erica Howton, Private User, Eldon Lester Clark. Scandalous Women comes to mind.
This is just to get us thinking more creatively about Best Of, I'm sure that there are categories, projects, and contributors galore that I have not remembered or am not aware of.