Synapse has released its line of VST instruments for Mac:

Our complete instrument plugin suite is now available in VST 2.4 format for Mac OS X Tiger. The plugins are universal binaries, thus they can be used both on Intel and PowerPC-based systems. Registered users can download the new versions free of charge from our service area.

Demo versions are available for free download.  The only restriction of the demo versions is that the plugins will not recall their state.