This is a softsynth that plays midi files, written in Delphi. This program is quite like Timidity, except it's newer, and it handles VST and VSTi effects - something that is VERY hard (imho) to fix in Linux. And as a great plus, it doesn't require Soundblaster.
All sorts of features, such as Note Cutoff, MIDI In, custom instruments (choose different soundfonts for different instruments in the program), dynamic memory management (it wont use 512 megs for a 512 meg soundfont, unless you use all the instruments).
Also, it can render to MP3, OGG and WAV (maybe some other formats, too).
There is also a program called Viena which is a substitute for Vienna, the soundfont editing program. As of a few versions before (at time of writing the current is 1.010), it is independent. Still, it too might be a thing to consider.
This is a pretty old version of Synthfont. It contains some bugs, but it is fully usable. Note cutoff adjuster doesn't work, so you'll probably get flooded with notes pretty soon with a complex midi file. But you can still render to .wav (this version doesn't support other formats).