I share screenshots fairly often throughout the day when I'm working on projects. Most of my communication is via email and chat so sometimes it's easier to just share a screenshot instead of trying to explain what I'm seeing. OS X already makes it incredibly easy to take screenshots but navigating through finder when you want to upload the screenshot isn't as smooth but easily fixed with Stacks, a built in Dock feature.
What we'll do is change where OS X stores screenshots and then we'll add that folder as a Stack in the Dock so it's easy to get to. Also, I highly recommend at least changing the default location for screen captures to be anywhere but your desktop, clutters up your desktop really fast.
First, let's go ahead and change the preference setting for where to store screenshots. Open up the Terminal.app and run the following command:
mkdir ~/Screenshots && defaults write com.apple.screencapture location ~/Screenshots && killall SystemUIServer
Now whenever we take a screenshot OS X will place it in your Screenshots directory, nifty. Let's go ahead and try it out.
Use the keyboard command
command+shift+4 and then click and drag over an area to take a screenshot.
It'll place that screenshot in your ~/Screenshots folder for you to use later on.
Now we need to add the Stack(expanding folder) to your Dock. Open up Finder and navigate to your home directory(
command+shift+h) and then click and drag the Screenshots directory to the right side of your dock. It just needs to be to the right of the divider and to the left of the recycle bin. Once it's in the dock I prefer the grid view for this type of folder since it's going to be images, easier to see/scan. If you'd like to change the view style just option+click and change the view style.
With your Stack(expandable folder) in your Dock you can now easily look through your stack to grab any of the latest screenshots you've taken and drop them anywhere to upload them. Here's a quick example utilizing Gmail but you can apply the same process to any application or website that supports dropping files on it.