The good part is that you don't have to sell, and the market will eventually swing up again (God does not make any more BEACH...) Many are not in as good of a position as you, and are upside down (they owe $ 440, and the home is worth only $ 380, so the only remedy they have is to lose the difference, foreclose, or ask the lender to allow a short sale. Either way, it's painful! Good luck, Kelly!
Appraisers are being very cautious these days. They are very careful not to overinflate the price of the homes due to the fallout in the subprime market. The prices in many markets have fallen drastically; I don't think we have had a major correction in SC.
It might be possible that the initial appraisal was incorrect. Who ordered the appraisal last year? Was the appraisal this year done by the same appraiser?
I am sorry about your current appraisal. You could always have another one done, but I seriously doubt that they will be $100,000 more than the one you just had done.