The craziest, wackiest soundfont editor has got to be Synth Font. (Free for download, donateware, Windows only).
I just poked at the buttons and hammered on sliders for a while and about half the time it would behave like I expected the other half was just wacky (a little too hard to give examples as they just wouldn’t translate to written word).
This application reminds of what it would look like if you threw an AKAI sampler over the swing-set and it turned inside out. It is without a doubt the labor of crazy obsession. No detail is left unresolved — for better or worse.
I will die long before I have time to dive into something like this very deeply for just random use, but there may come a time when I want to construct a complete universe of sounds and I think soundfonts are the most powerful sample- triggering technology. Especially when the software knows what to do with them. For all it’s cartoony and offbeat user interface, SynthFont seems to have a great backend , good sounding, very responsive and healthy on memory.
The editor itself isn’t bad and definitely the most powerful, flexible one for free I’ve ever seen.