All,
I normally don't promote web sites, but here's a web site by Andy Hertzfeld, one of the original Macintosh system programmers.
http://folklore.org/index.py The stories all have to do with first hand accounts of working at Apple around the time the original Macintosh was created, so not NeXT directly. But some of the key players such as Bud Tribble did go on to cofound NeXT. So some good computer history and some good background information on some of the people who later on founded NeXT Computer.
This site has been around for several years now, but it has been well maintained.
Brian