xxtraffic is a smaller, invite-based traffic-trading platform built for adult tube operators who want to swap exit traffic with peer publishers rather than go through a brokered ad network. The model is a classic ratio exchange - outbound clicks generate credits redeemable for inbound visits from other sites in the pool - which keeps acquisition costs near zero for publishers who can supply decent exit volume.
The platform is lightly documented and the member pool is narrower than larger networks; quality and volume depend heavily on who else is trading in your geo at any given time. Best treated as a supplement to paid sources, not a primary channel.