Big deal/not
I think virginity could be a big deal if the virgin wants it to be. After all, losing one's virginity is one of the great rites of passage. Having sex is a biological ability of an adult body, so the ability to have sex marks one as entering adulthood.
sacred/not sacred
Personally, I don't think so, but if someone really wants to wait until some predetermined point (for me, it was "until I love the person," and I don't regret it), I think it's admirable in that it takes a great deal of will and self-control to stay away from the combination of peer pressure, media saturation, and biological urge that push a young person towards sex. That said, I think a lot of people save themselves for the wrong reasons, and more than likely end up feeling let down when the moment finally comes; personally, I'm glad that I have a decent amount of sexual experience under my belt to call on when it's time to celebrate my wedding night.
something that can be sold?(should it)
I believe that a person's body is theirs to do with as they please, and that includes virginity. As long as both parties are of legal age and consent to the transaction, I really don't see any problem with selling one's virginity. Sure, they may regret it later, but how many people's first times are wonderful?
Promise rings?(pointless/stupid/good)
I personally don't think promise rings serve any purpose other than to allow religious organization to mark people as their own. A ring wouldn't prevent a teenager from having sex any more than a promise made to one's self. If anything, the ring seems to have the exact effect on some teens, constantly reminding them of sex and making sure it's on their mind more than ususal.
should you wait till marriage, love, or any opportunity?
I personally believe it's a good idea to wait until love (or what my teenaged mind was absolutely certain was love...), since both partners will be mutually caring and hopefully make the experience as pleasant as possible for each other. Of course, two virgins are likely to be clumsy no matter how much they love each other; likewise, someone may have a better experience if they lose their virginity to a more experienced partner.
In conclusion, I see virginity as something completely personal. I don't think there's any right or wrong way to handle it, but I think a lot of people need to think things through a lot more carefully and consider all the options.