A lot of people already do this but I can't find a protip for it.
I use Dropbox to sync my Sublime Text 2 plugins, settings etc. across multiple Macs. The same thing worked with Textmate too, and probably a lot of other apps.
First quit ST2, then run these commands in the terminal.
Create a folder
mkdir "~/Dropbox/Application Support"
Move the existing settings folder to Dropbox
mv "~/Library/Application Support/Sublime Text 2" "~/Dropbox/Application Support/Sublime Text 2"
Symlink the folder back to where ST2 expects it to be
ln -s "~/Dropbox/Application Support/Sublime Text 2" "~/Library/Application Support/Sublime Text 2"
This will also work for Sublime Text 3 but I've found that Dropbox will complain that it can't sync certain files because they are in use and "conflicted copies" will be created for many files. To get around this, I've turned on advanced selective sync in the Dropbox preferences and chosen not to sync Backup, Cache, Index and Local folders.