For ETFs that buy gold and other precious metals such as silver in addition to gold, here are two to consider.

PowerShares DB Precious metals (DBP), 80% gold.

iPath Dow Jones-UBS Precious Metals (JJP), 68.5% gold.  (Ratios will change, but as of publication those were the ratios).

These two funds use futures contracts – agreements regarding the future price of gold or silver for example – to track the price of a basket of precious metals.  As you can see above, these two funds concentrate on gold.