The City of Portland has good information available at the city's website, Portland Online, specifically, going to this page will take you directly to the page that not only has Portland cycling maps but also maps for surrounding cities.
They are free for downloading but, if you look in the middle of the page you'll find a link where you can put in a mail request. They'll gather up a handful of the maps you want, throw in a couple of pamphlets and a cool bumpersitcker or two, and send it off to you just for the asking.
That's right, basic good biking info for the asking. The above photo shows you what you'll get if you ask for the whole banana. And I suggest it; what with fuel prices being what they are, I think that people will more and more be taking to people power in the next few years to get round this town.