I use Yapta each time I buy a ticket anywhere to monitor for a refund but have never been lucky enough to get one. FYI, I don't think any of the airlines on Yapta offer cash refunds for a price drop...instead, you get a travel voucher or credit. Some of the airlines have other rules to minimize the credit/voucher amount. For example, American substracts thier ticket change fee from the amount of the 'refund'. They also require that the fare drop applies to the same booking code as the ticket you purchased and that it meets advance purchase requirements...and 'fare sales' are not eligible for a refund. No wonder I've never received a refund voucher.
This year we paid the most we've ever paid for non-stop tickets on American to MoBay - $690 per person from Dallas. I bought them about a week ago and the price is now $770 per ticket.