I was googling for some direction for a graphic design project on drug packaging, and stumbled across this: Healthcare Packaging website and magazine. Turns out - and I've known this for some time - you'll find a lot of trade publications available online for free. No doubt, it's the advertising that fund these babies.
Quick list:
Building Design and Construction has a free digital edition, that can also be downloaded as a PDF;
Concrete Construction has access to articles online, but not a downloadable PDF;
Metal Architecture has downloadable PDFs;
Boutique Design has viewable/downloadable PDFs;
Eco-Structure has viewable/downloadable PDFs of their issues and articles online;
EcoHome has archived issues in viewable/downloadable PDFs, and current issue articles online.