Here are some wildlife identification guides I've put together over the years:
> Cottonmouths and harmless water snakes of the middle Mississippi region: Link
> Most snakes rattle their tails, but only rattlesnakes have an actual rattle: Link
> What toad is this? Northeastern/ Midwestern US edition: Link
> What garter snake is this? East-coast edition: Link
> What egg mass is this? Spotted Salamander vs Wood Frog Link
> Cottonmouths and harmless water snakes of the middle Mississippi region: Link
> Most snakes rattle their tails, but only rattlesnakes have an actual rattle: Link
> What toad is this? Northeastern/ Midwestern US edition: Link
> What garter snake is this? East-coast edition: Link
> What egg mass is this? Spotted Salamander vs Wood Frog Link
Also, check out the Facebook Snake Identification Group, where I'm an administrator and moderator. We have over 200,000 members, and can usually identify a snake to the genus and species level within minutes. I'm also the creator of the Facebook Reptile and Amphibian Identification Group, which has fewer members (~25,000) but is still an active resource.