i just sold an art set and i thought the best way to give him the art is to email it to my buyer. He says to private to give away. Also i'v tried pm'in him the art and cant figure it out.
For heads or other invidual parts, image hosting sites are the best, photobucket is good for an example.
For sets, hosting sites are the best in my opinion, such as rapidshare, megaupload etc. etc.
photobucket has an album system, thats what i use.
or make a folder stick all the .tga files in there,zip it or RAR it(with winRAR) and upload that to box.net