http://golddetecting.4umer.net -- Gold Detecting and Prospecting Forum. Has been around a good while and is quite popular. A very good supporter of NAPFA from the very beginning. Organised charity fundraiser at Laanacoorie in the past couple of years.
http://brianjwalters.wix.com/dpfcclub-- Website for the Dubbo Prospecting, Fossicking and Camping Club. This is a very active club with around 3,000 members and is wellworth a look. They organise regular trips and count some NAPFA members in their number.