guidebooks and/or website?

[Kauri]

I have a Google map with marked pins on every (officially and unofficially) named DV canyon (and high point etc.) that I'm aware of as being of interest to hikers, with links to trip reports I've written on canyons I've visited:

https://kaurijacobphotography.yolasite.com (then scroll down to the map and click on each pin for the names)

Another resource (but more for canyoneers) is RopeWiki; I believe they have info and unofficial names for more DV canyons than I have on my website:

http://ropewiki.com/Death_Valley_National_Park

I recall reading a discussion somewhere about whether or not the authors of RopeWiki were really promoting responsible exploration of canyons or if some of their methods may be environmentally damaging. I don't know either way of the accuracy of this, but by referencing RopeWiki I don't claim to be endorsing any of their methods.

Michel Digonnet's Hiking Death Valley book has info on many canyons in DV, but is not a comprehensive list.

Steve Hall's webpage used to have trip reports and canyon names for most of the canyons that are of interest to DV hikers, but his website is no longer available online. This may be the website you were recalling.