I love Dropbox. It's a simple tool that lets you synchronize files between multiple computers (such as a laptop and a desktop, or a work computer and a home computer), and it even lets you share files with friends or coworkers who also have it installed. It syncs files in the background, so you don't have to wait to open them once you actually need them; once they're synced, they're stored on that computer's hard drive (although they're also available through a handy web interface). Useful stuff all around.
But, back in February, Lifehacker had an article explaining how to sync folders outside of your Dropbox folder. I could tell that was potentially useful, but it took me a while to figure out the powerful way to use this: syncing things like settings folders for applications.
The Lifehacker article has details for other operating systems, so I'll only be covering the Windows Vista versions of the trick here (see their article if you need to figure out how to apply it to your non-Vista computer).
Syncing User Scripts Between Google Chrome Installations
mklink /D "C:\Users\USERNAME\Documents\My Dropbox\User Scripts" "C:\Users\USERNAME\AppData\Local\Google\Chrome\User Data\Default\User Scripts"
Note: Once you do this, the synced folder will already be there when you get to your other machine. You may have to turn off Dropbox, rename that folder, then do this, and then copy everything over from the renamed folder (if you leave Dropbox on while you do that, it might break your link on your other computer, and then you'll have to do the whole process again, etc).
Syncing Digsby Chat Logs
While I love that Digsby stores my setup online (so it's all ready to go on whatever computer I use), it sometimes annoys me that the chat histories (other than Google Chat, which saves its own history) aren't always available; I have to remember which machine I was on when I talked to someone about something. Well, I used to. Not anymore.
mklink /D "C:\Users\USERNAME\Documents\My Dropbox\Digsby Logs" "C:\Users\USERNAME\Documents\Digsby Logs"
As with the Chrome syncing, you'll want to be careful about this, so you don't accidentally delete your other relative link. Also, you have to decide which set of logs you want to keep (or merge them manually, but that could be painful). I'm keeping my work logs, and copying them into the home folder (replacing duplicates).
I'm digging for more options like these. Let me know in the comments if you have other useful ideas.