Add .dropboxignore directory to exclude folders without using selective sync

Every time I see a response to this thread that isn't from someone at Dropbox (or IS someone from Dropbox giving an empty boilerplate answer) and I hate Dropbox that little bit more.

I suggest we give up trying to get Dropbox to treat us like customers they care about and instead use this thread to focus on helping each other: Let's continue to list Dropbox's competitors, along with their prices and all their pros and cons, in an attempt to find a decent alternative.