Currently on my VPS I'm running couple of sites and Dropbox daemon to store backups. Problem is that VPS has 512M RAM and it was enough until new version of Wordpress (I don't know why, but now it consumes more memory) so I have a really bad choice: either stop Dropbox daemon and backups or to buy more memory (not that expensive but still). So I'm looking for some way to rsync data into Dropbox or similar service or figure out how to make Dropbox consume less memory.
UPD: For now I've found a way to reduce memory usage. There's a ruby client for dropbox. It can be run as a daemon, but I'm not using it this way. I've configured my backup script (dead simple backup solution backing up database and directories to dropbox synced dir) to run its cron.rb script so new backups are uploaded. I didn't do much testing, but on my box I get ~90M RAM used by Dropbox official client and 20-30M used by ruby script. Also note that ruby script is ran only on demand. This is not exactly what I needed, but it solves the problem.