Expandable spray foam caught my eye when I was watched some "This Old House" episodes on the DVR recently. I'm not talking about Great Stuff, but rather the foam that is typically sprayed into stick framed walls in place of fiberglass or blown cellulose insulation. After it drys the excess is trimmed flush with the studs and drywall is applied. A quick Google search reveals lots of companies selling DIY kits but I wonder about the quality of the application equipment as well as the product itself. Has anyone here done it themselves?