Eyebeam has just launched Fundrace, a searchable database with political contributions searchable by either name or address.

Manhattan's top Democratic fundraising building, with 50K ponied up: 770 Park Avenue, with a Ziff, some Cullmans, Agnes Gund, even a Keating.
Manhattan's top Republican fundraising building, with just 29K: 85 Broad Street, which is all Goldman Sachs and a bunch of lawyers, especially Sullivan & Cromwell.

Use the search by name function carefully: do remember to use Sean Combs instead of P. Diddy, so you can see the 2K he gave to Al Sharpton — and Michael Bloomberg, for the 2K he gave to George Bush.

[Update: I knew y'all would have fun with this: Eve Ensler, Edward Norton, Steve Buscemi, and Treat Williams all live in the same building? That's a scary co-op board meeting. [Update: Oh, it's just an office address. Boo. Still. They all have the same agent? That's eerie.] Also, as Jason points out, Harvey Weinstein likes to cover all his Democratic bases.]
New York City [Fundrace]