As a tech blogger, I take a lot of screenshots, and I use Dropbox to make these screenshots accessible from any of my computers. Typically, the process involves me taking a screenshot and then manually uploading it to Dropbox. With GrabBox, however, I am able to automate the process.
GrabBox is a free Mac app. After installing it, it places an icon in your Mac's menu bar and opens an Initial Setup window. The setup involves one, simple action. It asks you to right-click on a file in your Dropbox Public folder, and it provides a button that will take you directly there. Click on a file in your Public folder and select Dropbox > Copy Public Link. With this, GrabBox links to your Public Dropbox folder and creates a Screenshots folder within it.
Now, when you take a screenshot on your Mac using the Command-Shift-3 (entire screen) or the Command-Shift-4 (a selection of your screen) keyboard shortcuts, GrabBox uploads the file to the Screenshots folder it created. It also copies the link for this file to your clipboard. By default, the screenshot is not saved locally. In GrabBox's Preferences, however, you can choose to also keep a local copy by checking the box for "Leave original screenshot intact."
In Preferences, there is also an option to have GrabBox prompt you before uploading a screenshot, but checking the box did not result in any prompts in my experience. It seemed only to disable GrabBox, storing screenshots locally per my previous setup. There is also a button to Change Dropbox URL, but I could not find a way to switch to a different public folder.
Two settings that did work were the check boxes for "Use random filenames" and "Make random filenames longer." By default, GrabBox gives your screenshots one-digit file names in sequential order. Clicking these options results in either 5- or 12-digit random file names.
As long as you don't feel the need to tinker with its settings, GrabBox is a great utility that can save you a step if you share screenshots on a Mac via Dropbox.