DropboxFramework
DropboxFramework was a port of the official Dropbox SDK for iOS to Mac OS X. It has no affilation with Dropbox, except that they have given me permission to publish this code.
I've since removed the code (though you can find it on the branch history), as
Dropbox have released their very own OS X SDK. It has many more features, is
actively maintained by Dropbox, and is definitely what you should use.
You can find it on their main SDK page.