Most of our customers use the native quotas...but to get windows groups or directory level quotas the only third party tools I know of are NTP (mentioned in the original post) which some of our customers use... another is Northern http://www.northern.net/en/Storage-Management/Disk-Quotas/ both companies have had booths at NetApp events and look like they do similar quota handling. The field reports tend to give an edge to NTP for maturity but at a higher cost.... but I haven't looked at northern in depth to confirm or give an opinion on the product. If there are any other third party tools other than these two, I'd be interested in hearing about them.