Extract is pretty brand new, so not so many people yet, but I've played with some previous incarnations (it was previously beta'd as a standalone web service).

Extract is pretty brand new, so not so many people yet, but I've played with some previous incarnations (it was previously beta'd as a standalone web service). That said, it's damned handy if you're turning a PSD comp into HTML/CSS. That's the use case it was made for - smoothing the workflow between the PSD-making designer and the HTML-writing coder. If a PSD comp has, say, a button with a gradient and a drop shadow, then Extract gives you CSS to reproduce that design, without your needing to open Photoshop and copy/paste the gradient colors and so forth. Even does a pretty good job of including prefixed CSS when needed. My experience was, for reasonably well-formed comps it's a godsend. For pathological PSDs it's less useful, but you're still better off with it than without it. But it all depends how often you have to HTMLify PSDs.