Posting images in most message boards involves uploading the image to a host, copying the URL, and then enclosing the URL in Bulletin Board Code [img][/img] tags. This service uses the Imgur API to reduce the steps in the process to one control-click.
Register for a free Anonymous API Developer Key. Then, choose a Service template in Automator that receives files or folders in Finder and paste the AppleScript below into a Run AppleScript action. Enter your API Key in the apiKey property.
property apiKey : "enter your api key"
The script will populate your clipboard with a URL that is ready to post. If you simply want the URL without the [img][/img] tags, change the img_tag property from