1. Download the latest Dropbox .tar.gz source files (direct link) and unpack it.
2. Install libnautilus-extension-dev libnotify-dev and python-docutils:
sudo apt-get install libnautilus-extension-dev libnotify-dev python-docutils
3. Go to the folder where you unpacked Dropbox (at step 1) and run the following commands in a terminal:
./configure make sudo make install
4. After installing Dropbox, restart Nautilus:
Then press Alt + F2 and type: nautilus
Now go to Applications > Internet and you should see Dropbox listed there.