This is a great new application which does one thing very beautifully: it previews a dropped markdown file, and updates when the file is saved. You can have the window open next to your editor window, and get a Markdown preview plus word/character/line count for free, with any editor.

There are loads of camera/filter apps around, but this looks like a nice balance of ease of use and good results. Just wish it shared to Flickr too, though.