I think most companies have a first aid kit available to their employees. The place I work with is a health insurer so they stock up more than the average facility. They have the usual bandages, but also different types of cold medicine, allergy medicine, eye drops, etc. I use their offerings regularly in order to save money.
Yes they do and I too take advantage of it. For me it isn't the saving money, although that is a nice perk now that you mention it, but I like not having to carry a small first aid kit with me or store it in my desk.
My company does as well, but the only time I use the OTC drugs is if I don't have anything with me. I usually carry a lot of my own products, but just in case I don't....my work place usually does. I don't take a whole lot of OTC drugs though, so when I do buy them, they last me for quite some time.