I've been using my half filled log book from my sailing days as a field book. Waterproof paper; stitched binding etc. I've almost filled it up and am looking for another; There seem to be a gazillion manufacturers and styles...Can't say I'm thrilled about the gaudy orange and yellow covers (mine's a subdued brown), but imagine my opinion would change the first time I drop it in the woods and can't find it.
Any favorites?
You can always buy sheets and put it in blinder. I prefer a simple yellow field books, its easier to carry and write it.
http://www.hayesinstrument.com/cgi-bin/webc.cgi/st_prod.html?p_prodid=2726
If you want waterproof, Rite-in-the-Rain is the brand you want to look for. Most survey supply outlets either carry them or can get them easily enough. If your local community has no such place, there are several that you can mail order or internet order from, including Hayes, Allen Instruments, and a few others.