App to sync PDFs between Linux laptop and Android phone? I like reading research papers on both my laptop and on my phone.  I'd love to be easily send a PDF to the phone while reading it on the laptop, so I can read it later on the subway or when I am someplace without a network connection.

I've tried Evernote with the web clipper plugin on my Linux laptop, but that will only remember notes that contain the PDF URLs rather than the PDF contents directly.
I can recommend https://www.dropbox.com/
At the moment I have it on Ubuntu, Windows 7, Mac OS X and also on HTC Desire HD