I heard someone I know had gotten a gift card by transferring their prescriptions to another drug store. Apparently the trick was to call the pharmacies and ask them what kind of offers they had since they didn't necessarily publish their offers.
I did a little hunting on Google and found some references to this. Theres an article Transfer Prescriptions for Fun and Profit from MoneyBlog on MSN. They got a $25 incentive from Safeway to switch. I also found several references to such offers from various pharmacies in previous years.
Right now RiteAid has an offer to give you $30 to transfer a prescription to them. There might be other pharmacies with current offers also. If you call around other pharmacies then they might be willing to match the RiteAid offer, it wouldn't hurt to ask.
If you have an ongoing prescription and are open to switching pharmacy then this might be an easy way to make a few dollars.