Reddit mentions of Spiders of North America: An Identification Manual

The identifying features of spiders are more subtle than they are for birds or butterflies - like eye arrangements, length and number of hairs on their legs. Also, consider there are about 900 species of birds in the U.S. vs. about 3,000 spider species. Just trying to help you understand why you're having a hard time finding such a guide.

My favorite spider field guide is the Golden Guide to Spiders and their Kin. Though the book includes spiders worldwide, it focuses on American species, and the description of family features can inform ID anywhere. There is a 1990 edition available in full online. Some of the taxonomic names have changed since then, but you can get the idea. You can't beat it for the money.

I don't have this one, but browsing it, it looks pretty nice.

Otherwise, the technical standard is SONA.

Alternatively, invest in a camera: take pictures and share them with us -- we are always here to help. Bugguide.net has detailed descriptions at almost every taxonomic level.

Maybe you could start by keeping one as a pet like everyone else lol. It's honestly a lot like having a fish. If you're feeling really bold you could try reading the short communications or other papers on the American Arachnological Society website. Good starter books:

1. (easiest to read) http://www.amazon.com/Arachnids-Jan-Beccaloni/dp/0520261402/ref=sr_1_1?ie=UTF8&qid=1317949575&sr=8-1
   
   
2. (slightly harder) http://www.amazon.com/Biology-Spiders-Rainer-Foelix/dp/0199734828/ref=sr_1_1?s=books&ie=UTF8&qid=1317949592&sr=1-1
   
   3)(really hard spider identification book that goes through collection methods, microscope use and more)http://www.amazon.com/Spiders-North-America-Identification-Manual/dp/0977143902/ref=pd_sim_b5