I am rather conflicted about Valentine's Day. Not because I have problems with the tradition of gift giving or extravagant gestures: by the same token, Christmas, birthdays, anniversaries, and many other holidays are also more about expectation than anything else. I agree with Will and Heidi that the imposition of ill-fitting and unrealistic traditions can be unhealthy for a relationship, but if you assume the following conditions:
1. There are certain cultural traditions which we enjoy participating in, even if we don't buy into them entirely. Witness the vast numbers of atheists, agnostics, and members of other faiths who somehow get into the Christmas spirit.
2. Like a penguin with a pebble, you desire to give gifts to your significant other as an expression of affection and as means to bring them pleasure. If love is the internalization of another's utility function, and you know that certain objects or experiences would delight your significant other, then this seems natural.
3. Some gifts require saving up for or preparation.
. . . then it seems like you have to pick one day on which your SO will get a special gift, so why not have that day be today? Valentine's Day doesn't mean candy hearts and fairy princesses, and it doesn't have to mean bad food and poor service. It's just a convenient time to express your appreciation for another person. Whether you do this with dead plants, migraine inducing chocolates, or gifts that are targeted to the individual's idiosyncratic interests is up to you.
My main beef with Valentine's Day is that it's tacky. There are a lot of hideous bouquets, trashy-looking negligees, ugly stuffed animals, and waxy chocolates floating around. So if you decide that 2/14 is a good day to give your SO the cool thing you've been meaning to give them anyhow, make sure that it's something tailored to their interests and not some piece of cheap red plastic.
Anyhow, happy Valentine's Day to all you lovebirds, and special congratulatory wishes go out to Mr. Sandefur, who is spending his day with a fiancee, not a girlfriend. I suppose this means the posts about hot chicks that so irritated me are on permanent hiatus. All hail the civilizing effect of woman.
UPDATE: Dirrty girl C. Aguilera is engaged, too. I will bet $100 that her wedding won't be as tacky as Britney's.