Here’s a cool, well-done site: Portlandbeer.org. It’s still a little nascent, but here’s what they say on their front page:
What we are: A group of volunteers who have taken it upon ourselves to make sure that Portland, and it’s visitors, can make the best use of our greatest natural resource: beer! By maintaining an up to date listing of Portland beers and breweries, we hope to connect you with the beer you you’re looking for.
What we are not: This is not a Portland beer and brewery review site. Everyone has a different reaction to different sights, sounds, and tastes. We are not here to tell you what to think, but rather tell you what is out there and how to get to it. We think that it’s much more fun to drink beer and make your own opinion.
On their Breweries page, I’m a little surprised that they only list 14 breweries… but I suppose those are the ones that are exclusively within Portland city proper? (As opposed to some of the outlying towns… I’m used to considering that entire area "Portland" even though it’s not.) On the other hand, they also list the various locations each brewery has (check out McMenamins!), so there really are a lot more options than "only" 14.
Check out the Beers page too: that page is gold. You can sort and filter by beer name, style, brewery, and whether it’s a seasonal or not; and the beer icon next to the name is (roughly) color-coded to the style of beer. Nice touch.