Most people opt for the uber-popular SPDR Gold Trust (GLD) or iShares COMEX Gold Trust (IAU), but many of the goldbugs I talk to eschew these ETF for physical gold or shares of gold miners.
Goldbugs are buying bullion for the understandable reason that central banks appear committed to printing more money: they fear that eventually this will lead to inflation.
For those into just buying bullion or coins a lot of goldbugs recommend The Tulving Company at www.tulving.com, but I have no personal experience with them.