Early on in our house project I spent many hours in the woods looking for the right arched beam to cross my office. I found a lot of really great straight trees.
More recently I've been looking for nice straight floor joists and see nothing but great curves for the 'next' frame.
I got that cruck itch really bad watching a slide presentation given by Jack Sobon at Heartwood School. I'd keep my eyes open for his next workshop or appearance at someone elses.