OplEdit

Features:

• it works
• allows you to interactvly play and modify patches
• uses external midi or any other program that speaks midi (see 'clavier')
• works with standard OSS Lite driver.
• reads and writes both 4 and 2 operator SoundBlaster SBI patch files.
• more to come...

main window (gif)
with clavier program driving it (gif)

Here are a few random patches I found on net, many crappy ones because they try to emulate real insturments, try modifying them, FM is good at creating ambient and bass type sounds as well as very 'electronic' sounding stuff... fool with it, you can make some pretty neat sounds

sbi2op.tar.gz 1198 2-operator patches
sbi4op.tar.gz 120 4-operator patches

here is some random technical documents and waveform pictures I have collected.
and the clavier program: http://www.sdf.se/~simon/clavier.html