Hi,
This is a plain old linklist, which should help to get you to the info you need
Gnutella for Users - Gnufu - Basic infos how Gnutella works.
Links - A basic linklist with most resources which are available.
Normally that would suffice, but I'll add basic links in this forum, too
Program.Gnutella - A precise description how to write for the Gnutella network.
http://rfc-gnutella.sourceforge.net/...ing/index.html - the outdated specs
Specification - Specifications in a wiki, more recent.
Gnuticles - Dev-Infobits: Infolets for Developers - smaller infobits. (handshake)
IF you find some more important links, please add them.