Digging for resources can be a significant amount of my time when I'm working on something. For that reason, I've got a pretty extensive boat-building library here at home that I've posted about before. It's not as extensive as the library at WoodenBoat's office - I really wish that I could get there more often, because it's pretty impressive. Inter-library loan often has some of the books I'm looking for.
Another place that I go looking for information is the Web. The Wooden Canoe Heritage Association (WCHA) website has excellent canoe-related resources and the WoodenBoat Forum has more general boating-related. Qajaq USA has some neat things related to traditional kayaking - specifically Greenland-style kayaks and accessories.
One of the best places to go is to trade-shows. Vendors of materials, hardware and as well as builders and designers. Other home-builders at these shows are often willing to talk about their craft and some of the lessons that they've learned. I often find that you learn more from the amateurs than you do from the professionals. There is not substitute for getting out and talking to people.
Museum are fantastic repositories of the unique, the rare and the historically important that you'll find nowhere else. Many have both books, documents and artifacts that you can review if you're willing to take the time to make an appointment and go work with an archivist. Places like Mystic Seaport, The Penobscot Marine Museum, the Adirondack Museum, the Antique Boat Museum, the Canadian Canoe Museum, the Peterborough Museum - I could go on and on.
Resources for paddle and oar making are pretty thin, indeed. They are generally treated as an after-thought in books on boat building and usually a chapter in the rear of the book is devoted to the construction of paddles or oars. While anyone can make a paddle, it takes some knowledge to make a great paddle - things like design, and performance issues, wood selection and aesthetics - let along, fitting for the user and the boat.
I know of two books on Greenland Style paddles, one on canoe paddles, and none specifically on oar or double-bladed paddle fabrication. The Greenland style books are available from Brian Nystrom (Greenland Paddles : Step-by-Step) and Qajaq USA in the form of a free PDF written by Chuck Holst - Making a West Greenland Paddle. The two best resources that I've found for what I'm doing are Murat's aptly named blog Paddlemaking (and other Canoe Stuff) and the book, Canoe Paddles : A Complete Guide to Making Your Own. by Graham Warren and David Gidmark. Graham also runs Moosehead Canoes and Paddles in the UK and offers great information there and DVD information on paddle making.
What are some of your sources of information?