It is not still complete, but here are some more people.  Mostly I
found them on Google.  (Thank you, Abe-san!)

-- Yoshiki

* ky is Koji Yokokawa ("ykoubo" is him, too)
* RAH is Richard A. Harmon  (ScaledDecimal)
* miki is Mikael Kindborg  (FileChooser)
* jdf is David Farber 
* GVG is Greg Gritton
* gwc is Geoff Corey 
* hjh is Hannes Hirzel
* jbc is Jay Casler 
* jdd is John David Duncan 
* jwh is Jim Heyne 
* JZH is John (Zhijiang) Han 
* kafka is Pablo Malavolta 
* mkd is Michael Donegan
* phk is Peter Keeler 
* pmm:  author of Scriptaculous-pmm 
* RCS is Russell Swan
* rew is Roger Whitney 
* rj is Ranjan Bagchi 
* RJT is Ron Teitelbaum
* rmf: somebody who did CPPPluginEnh
* sac is Scott A Crosby 
* TEM is Tom Morgan
* tetha is indeed Tetsuya Hayashi
* MAL is Michael Latta
* umur is Umur Ozkul
* wdc is Bill Cattey 
* TBP: somebody who worked on AudioChat in early 2000.
* YE: author of SkipListTest (in March 2006)
* dls: soneone who wrote ArchiveViewer>>initializeToStandAlone in 2001.
* ASF: someone who wrote FileUrl>>retrieveContents in 2005.