I'm personally very wary of posting ads on Craigslist because of their TOS. If it's working for anyone, then all power to you, that's the truth, but just be careful.
I've never joined GetRef but I am a member of DownlineRefs. It's an iffy type of thing. One one hand, if I'm ready to join a new program I often look there first, so at least I'm getting some form of ad credits for joining. But a lot of the users are dishonest. Sometimes they sign up and then do nothing. You can terminate their contract, but that results in a drop in your own referrer rating. On the other hand, sometimes you can sign up for a program and someone with a super high referrer rating can then terminate your contract so they get their points back.
I think sites like that are OK but I wouldn't use them as my sole basis for referrals.