I stopped using Dropbox when it started asking if I want to back up every USB drive that I plug into my PC, and started to pollute my removable drives with a configuration file. (Because for some reason that's the only way it can know that I don't want my removable drives backed up.)

All I've ever wanted is a folder that syncs automatically. Nothing more. And for a while Dropbox was the best at fulfilling that role and getting out of the way, but it seems feature-creep has taken over.