First post, by yawetaG
While looking for a specific software editor for a MIDI module, I found this archive with tons of descriptions and links to old module and synth editors:
http://www.hitsquad.com/smm/archive/
Also found this page with some useful utilities:
http://www.hermannseib.com/english/midi.htm
And this one that lists various XG editors for a specific Yamaha synth-family:
http://www.webring.org/l/rd?ring=xg_for_all;i … software%2Ehtml
Of course, there's also XG Central, but that one is pretty well known:
http://www.xg-central.com/xgc-software.php
Some of the links are dead, but that's where the Internet Archive (http://www.archive.org) comes in handy...