http://www.ntcip.org/ National Transportation Communications for ITS Protocol
US Federal Highway Administration project working on, among other
things, a new network control protocol for PPP.
ftp://ftp.uu.net/doc/lpf/ UUNet archive of LPF documents
(Warning - the old "lpf.org" domain has been taken over by the
Libertarian party in Florida.)
(The LPF seems to be stirring after many months of inactivity.)
http://www.hifn.com/ HI/fn now has all of the rights
to the STAC and MS-PPC compression algorithms, and sells source code
and compression chips for PPP implementations. The old STAC Electronics
site still exists, but has no compression references.
http://www.macorchard.com/connect.html
http://www.macorchard.com/ A dozen different free PPP and SLIP implementations and related
utilities for the Macintosh. The main page for The Mac Orchard, listed
second, contains a large number of references for general Macintosh
networking software.