Locally made Valentines Card for the lumberjack/lumberjill in your life, from Bitches & Beehives:
Check the Valentines Day specials at several fine restaurants over at Portland Food Map:
You can try to snag one of the gigantic heart banners that will inevitably be put up by the infamous Valentines Bandit. It would make a good decoration for any (large) room:
I hear flowers are a good gift, and there are several fine florists around town. I recommend Sawyer and Company at 737 Congress Street because I have a picture of their charming store:
Lastly, chocolate is always a good idea. Unless your Valentine doesn't like chocolate, in which case you should buy him or her some other type of candy at Old Port Candy Company.