Arif Bilgin, AT&T Research (smyrna and Windows support)
John Ellson, AT&T Research (Tcl/Tk and codegen extensions)
Emden Gansner, AT&T Research (dot, neato, twopi, circo, fdp, osage, smyrna, gvmap, prism, gvpr)
Yifan Hu, Yahoo (sfdp, prism, gvmap, cluster, mm2gv)
Stephen North (dot, neato)

and

Yehuda Koren, Google  (neato)
Don Caldwell, AT&T Research - retired (map labeling)
Vladimir Alexiev (codegen improvements)
David Dobkin (spline-o-matic)
Tim Dwyer (IPSEP-cola and DIG-cola extensions to neato)
Eleftherios Koutsofios, AT&T Research (dotty, lefty, spline-o-matic)
Bruce Lilly (pic driver)
Glen Low (Apple Mac OS X port; the page icons on this site; cgraph patches for dot)
John Mocenigo, AT&T Research (Grappa)
Jeroen Scheerder (allow URLs in PDF distilled from Postscript output)
Richard G. Daniel (RPM packaging)
Gordon Woodhull (Dynagraph)