Another option, which I use, is an "Action" folder. Quite literally a folder named "Action" in my Dropbox folder (~/Dropbox/Action/) where I will dump incoming files for Hazel to process them and then move them somewhere else.
This allows me to have a centralized location for my Hazel actions, as well as not having to worry about Hazel re-processing files if I rename them, etc. once they are moved to their final destination.
For example: if an app will allow me to set its backup folder (for example, BusyCal), I will use ~/Dropbox/Action/ and then have Hazel archive the BusyCal backups and move them into ~/Dropbox/Backups/BusyCal/ which is where they will remain.
The other advantage to this system is that I can have all of my Macs add files to ~/Dropbox/Action/ and then have one Mac (a Mac mini which runs 24/7) take care of running the Hazel rules or whatever else I want to do with files that end up there. That way I don't have to duplicate my Hazel setup on all of my Macs.
This also has the advantage that if something goes awry, I can 'undelete' the files from ~/Dropbox/Action/ for 30 days using the Dropbox.com interface, so if Hazel does something I did not want or expect, I can get the originals back.