Manufacturer coupons (GOOD) are discounts offered by the company that manufactures brand name medications and so are only good on one specific medication. Sometimes these are for a free first-time fill and others do a continuing discount on each monthly fill. These can be applied on top of your regular medical insurance UNLESS you have government sponsored insurance (Medicaid and/or Tricare). In rare instances, some people end up getting their prescription for free. Once again, these are really only available for brand name medications (not generic) but they are usually the crazy expensive ones anyway.
Where can you find these marvelous things? They are often available at doctor's offices (whence they have been placed by pharmaceutical sales representatives hired by the company that makes the drug) but you can also often find them online (I usually start by googling the drug name or trying <brand name>.com, e.g. advair.com). We used to have a stack of them in the pharmacy but that is becoming less common as pharmaceutical sales representatives are discouraged from visiting pharmacies for fear they will affect prescribing practices (please insert eyeroll here; I will save this soapbox for another day).
I did also run across another website that might be helpful for anyone trying to pay for prescriptions without insurance. The Partnership for Prescription Assistance is a central place to access the variety of programs available to help pay for prescription medications (the majority of these are basically manufacturer coupon programs). CAVEAT: I have NOT actually used this site but it looks legitimate to me and I think it would be worth a try.