I put a two-tiered display into place - nonmembers see the "free" thumbnail service which provides thumbnails for those sites listed in the DMOZ. My paying members see the paid service provided which provides for thumbnails of every site listed in the index.
Donate to UBBDev today to help aid in Operational, Server and Script Maintenance, and Development costs.
Please also see our parent organization VNC Web Services if you're in the need of a new UBB.threads Install or Upgrade, Site/Server Migrations, or Security and Coding Services.