Add .dropboxignore directory to exclude folders without using selective sync

No doubt Dropbox is a company which places importance on simplicity. However, if they're worried about adding complexity, I would recommend adding it as an undocumented feature. Maybe just a mention in a changelog somewhere. Then people all over the internet will write tutorials on how to do it - and the people who are looking for the feature (developers / advanced users) will have no trouble finding this information - not to mention go on to passionately share Dropbox with colleagues, friends and family.