I've been using this addon for a few months now mainly on the Ozbargain website which uses Markdown Extra. It's helped save me time and is convenient to link. 5 stars!

UPDATE: It's been 4 years and it's still going strong!

This works great with my blog using Markdown, and also for pasting pages into GitHub issues. I miss the old "Copy as HTML Link" extension, but for a lot of the web applications I use now, this is better.