For legitimate ordering of prescription drugs, CanadaPharmacy seems to be very good, efficient, and trustworthy.
Note, THIS IS NOT SOURCE POSTING. They require that you fax a full prescription to them AND give contact information for the doctor who gave you the prescription so they can verify. They also will only work with you if your state laws allow importation of prescription drugs. Even then they only allow 90 days worth.
You may ask, what's the point? The point is if you, a friend, or someone you know doesn't have a prescription plan, it is likely FAR FAR cheaper to order through these guys than through a local pharmacy.
As a note, if a pharmacy is not licensed with the FDA or any other major health authority, then they are likely to be very shady no matter how professional their site may appear. With those types of pharmacies it becomes difficult to determine what kind of quality assurances you may or may not have with regards to your order. Basically you'll have the same chance of ordering fake products as you would with any unverified source. Don't expect them to be more trustworthy just because they claim to be a pharmacy.