AVOID AT ALL COST:
Those cheesy HUGE valentine's day cards!
Lingerie...
Small appliances
Gifts that are for you, and you're passing off as a gift for her (LIKE A TV... AHEM)
No x-of-the-month gifts. That is such a cop-out. Think about the gift yourself.
Stuffed anything, unless it's food!
Here are things I'd LOVE to get (too bad my husband doesn't read this forum):
Flowers
Chocolates or treats (cake, cupcakes, chocolate covered strawberries, cookie bouquet, etc!)
Dinner & a movie (either get take-out for home from her favorite place, or go to a nice restaurant)
BALLONS! They make it seem like you are making a big deal JUST FOR HER!
Look into her hobbies, things she likes to do. For me it'd be--
Camera equipment for my Nikon
Books
That new LED flashlight I want to candle eggs with 115 lumens that's about $30
A really nice incubator
A BOX FULL OF BABY CHICKS!