Although no longer directly involved in the yahoo group, Helmut is the man who made all of this possible. He built the first version of the panotools from scratch and continued development until ugly corporate bully ipix threatened him with legal action based on questionable patents.
In 2003 he published PTViewer 3 which can display HDR scenes and PTViewerME for mobile devices. Recently he published PTViewerNG, a prototype for a WebGL/HTML5 spherical panorama viewer and PTStitcherNG, an ultra fast streaming panorama stitcher which is partly compatible with his old PTStitcher and supported by PTGui. His current interests can be seen on his page http://webuser.fh-furtwangen.de/~dersch/. His creation lives on in the contribution and work of many devoted software developers and photographers.
Thank you, Helmut!
A mirror of his original panotools page (prior to shutdown) can be found on http://www.panotools.org/dersch