I think this may be one of my absolute favorite dresses I've seen on my daily Internet travels (at least I'd call it a dress). This is the Oversized Overall by Einat Burg's label, FROG (remember those gorgeous neckpieces?), and is available in The Shop. If it wasn't this time of the year, I would definitely snatch it up. First of all, it's one size. Second, it features that billowy leg I've been after lately. Third, it can be machine washed. And fourth, and most obviously, it's incredibly beautiful. I would have a hard time picking the colour though, as it's available in black, grey, or blue...Sigh.
There are also some more pieces from the FROG 09 collection that have this lovely versatile/convertible/layering style (some of which are also available here). Just perfect. They would all be right at home in my wardrobe.