I have been using Github Issues recently and loving its simplicity. Unfortunately, I’ve found that I often need to upload screenshots to demonstrate bugs and Issues does not support file uploads. There are Windows and Mac applications that solve this problem by capturing a screenshot, uploading it, and copying a URL to access the screenshot to the clipboard.
I did not find any Linux applications that will capture/upload a screenshot and copy the URL but I discovered a thread in the Dropbox forums with a script that does just that. I added comments to the script, changed the variable names, removed the need for a temporary file, and added a notify-send call as a visual cue (should work on Ubuntu). I have the script mapped to Ctrl-PrtScrn in Ubuntu.