Skitch

 Skitch  is an application for OSX which can take screenshots, add annotations, and share the images to multiple destinations such as Evernote, FTP, or a WebDAV endpoint.

Skitch 1.0
After being acquired by Evernote, Skitch 2.0 removed the ability to share to WebDAV endpoints.

You can still download the last version of Skitch 1.0 from Evernote here: http://get.skitch.com/Skitch-1.0.12.zip

Use with IndieWeb Sites
Because Skitch supports sending files to a WebDAV endpoint, it is possible to use Skitch to post screenshots to one's own website, assuming the website supports WebDAV.

p3k supports posting images via WebDAV into an "uploads" folder since 2014-02-10