SynthFont 1 is a free tool for playing/rendering MIDI files using SoundFonts and other similar sound sources (WAV, DLS, GIGA and also VST Instruments).
SynthFont2 is the second generation of SynthFont and has a number of new features and improvements. It costs €15.
SynthFont is intended to mimic the behavior of SoundFont compatible hardware/soundcards like SoundBlaster Live! or Audigy and SynthFont is (almost) modulator aware, which Live! is not. But SynthFont is more. It provides an interface into the SoundFont structure and has basic editing capabilities. It also displays various data about the loaded MIDI file through the piano roll and the event list. Finally, there is a simple playlist feature for storing the files you are currently working on.
SynthFont also supports VST effects - there are 17 busses in all: one master bus and 16 channel busses.
VSTSynthFont (VSF), a separate VST instrument version of SynthFont is also available.