Today I discovered several people have been writing up ways to use Little Snitch to hold down LTE data costs as tethering becomes more common. The idea is to have Little Snitch clamp down on data hogs, like Dropbox, iTunes, and online backup services, when you are tethered so you don't burn through your LTE data. Eddie Smith and Guillaume Ross have both covered the technique admirably and it is enough to get me to re-install Little Snitch after not having used it for years.
I particularly like Eddie's footnote about Dropbox and how he gets burned when people he shares folders with drop files in his Dropbox account with no warning. Having written a media rich book with Eddie, I'm pretty sure he could have changed that to read he gets burned when David Sparks shares large files with no warning.