I already know about using s, m, or l at the end of my Imgur link to generate a thumbnail. Almost always when I do this, I want the thumbnail to link to the original image, so all my images end up like this:
or like this:
[![description]] : http://i.stack.imgur.com/stuffm.png : http://i.stack.imgur.com/stuff.png
and after taking two tries to get the URLs the right way around and all the brackets in the right place, I reflect on whether anyone at SE has heard of DRY.
This is such a common need that the uploader gadget (the one you get by clicking the icon) does it for you. That's fine if you're uploading the image to start with, but most of the time when I generate this idiom it's because I'm editing a post made by a new user who broke it somehow, and that option is not available to me.
A better solution would be if the page formatter automatically added the link. That is, when the HTML is generated, any imgur thumbnail which isn't already inside a link gets wrapped in a link to the full-size image. That would make it harder for new users (and experienced users!) to get it wrong by accident, make the Markdown source easier to understand, make it much easier to edit posts and review edits, and improve the quality of posts across the network.