HammerSound Soundfonts (Size: 874.81 MB)
This is a complete scrape of the SoundFont (.sf2) archive at the excellent HammerSound website, http://www.hammersound.net.
These are all freely downloadable from that site, or from its mirrors, but
the message is always "we need more mirrrors!". This is an attempt to
alleviate load on the mirrors.
The soundfonts themselves are of varying sizes and quality, and in varying
compression formats. The HammerSound website contains user feedback on these;
you should browse the website to determine which ones might best suit your needs.
Linux users should check out the excellent fluidsynth. Timidity++ also has
support for soundfonts these days.