Most freebies that I have seen in this subforum are in the form of goods. I think it has to do with the fact that a freebie in this form is easy to quantify and doesn't cost the giver or issuer the element of time to deliver it which is not the case with freebies in the service industry or, I might be wrong. Have you ever received freebies in form of services?
I've never seen people offering free services to be honest as it just takes too much time and effort to give the customer satisfactory results. With free goods & products all you have to do is deliver the product to the person that requested it and they'll be happy with it.
In the barber shop that I patronize, the freebie is a short massage of the head down to the upper part of the body. Although the massage is only for 5 minutes, it is a good service considering it is a freebie only. But the free massage is only rendered to long time customers of the barber shop as a way of goodwill.
I haven't really seen such service being announced over a website. However, in local shops there are always offers like buy a watch and get it serviced free for sometime. Like the other day I bought a watch and didn't like the straps. They exchanged it for me with my choice straps and even shortened the strap as per my desire right there and then. Similarly many clothing stores offer free alteration services if you buy from them and give you within few minutes while you check out the rest of the mall or complete your other work.