There's been a couple posts lately looking for some items which, at the time I couldn't remember the names of several sources I knew about. I've since found them and wanted to share these with you for future referencing.
One item was for a watershed system applied below a deck. There is one called DrySpace, with info available at www.dryspace.cc Have not personally used this one, but had some info on it. Looks like a reasonable product that would be very DIY friendly.
Another I was reminded of by posts for false beams. This is Fypon; great stuff! Just about anything available in the way of lightweight and weatherproof moldings, trims, columns, etc. Thier site is www.fypon.com