Dropbox - dnschneid/crouton GitHub Wiki
Don't try this on ARM
After getting Dropbox to compile and run, it complains that it's missing the proprietary daemon, which is impossible to download anywhere for the ARM (new Samsung $249 chromebook). Monitor the feature request here. [ This section needs update.]
For x86 and in case the daemon is released
Use apt-get if you can:
sudo apt-get install nautilus-dropbox
If not, this is a work in progress to help compile dropbox by source. Note the missing packages may differ for your distribution. This is for the default XFCE.
sudo apt-get install libnautilus-extension-dev python-gtk2 python-docutils
Download the source and follow instructions at https://www.dropbox.com/install2
./configure; make
sudo make install
./dropbox start -i