An excellent guide to offbeat Portland is Chuck Palahniuk's Fugitives and Refugees. Also try Geek Love, by Katherine Dunn.

If you plan to visit Portland with your dog or if you are considering living in Portland, A Bark in the Park by Lisa Johnson is a great source of information on where you can take your dog and which parks allow dogs off leash.  

If you are interested in Hiking, Portland Hikes : Day Hikes in Oregon and Washington by Art Bernstein is a good guide to day hikes within miles of Portland.

Got Shade by Carolyn Harstad is a lovely gardening book, addressing the particular needs of a gardener in Portland and the rain.