Obviously there's quite a bit of clay you can work with, since that's the majority of EC/PC. Flood offenses use almost entirely CoW and FoM cards, and Guardian ran a very successful Silver/Orange deck with a lot of RoJ cards. You can make some pretty great decks around CoW Moses, as several people have shown (Gabe won nats with a Moses deck without even running SoG!).
Many of these, if built correctly, will still include cards from older sets, but the core of the deck is newer. This is by no means exhaustive, just a few ideas off the top of my head.
