Gold can catalyse many reactions. Hong C. Shen summarized homogeneous reactions forming cyclic compounds into 4 main categories (DOI DOI):
* heteroatom nucleophilic addition to unsaturated C-C bonds
* Hydroarylation: basically a Friedel-Crafts reaction using metal-alkyne complexes. Example, the reaction of mesitylene with phenylacetylene (Teetz & Sommer 2003 DOI):

* Enyne cyclization, in particular cycloisomerization with early example 5-exo-dig 1,6 enyne cycloisomerization ((Nieto-Oberhuber et al. 2004 DOI)

In this type of reaction gold does not interfere with the alkene group.
* cycloaddition reactions: early example the cycloaddion of an nitrile oxide with an alkyne (Gasparrini et al. 1992 DOI)

Other reactions:
* The use of gold in C-H bond activation (DOI).
* Itoh Aldol reactions (1990's)
Update Feb 2009: Corrected Nieto-Oberhuber image (thanks to vigilant reader!)