When you say "when you give them another members name" I assume you mean MEMBER SERVICES?? Is that correct?
DVC members can and do receive some kind of incentive ~ it's been a while since I've come across what the incentives are and I haven't recently had occassion to be eligible. I do remember filling out a post card with my member name and maybe membership # (can't recall) with the person who I said was interested for MS to get in touch with as to be eligible if they ended up buying into DVC. I think it was $200 reward credit or something to that effect. I'm sure someone will come post who is more knowlegeable.
But in any effect, unless they've discontinued it, they do give already exisiting members some kind of incentive to referring people to buy directly from Disney if they are to sign.