I am a KDE user for nearly ten years and for the last four or five it has been my principle personal working environment (Windows XP/Vista being necessary only for some activities related to my work). I use Slackware as my Linux distribution and am currently running Slackware 12.1 and 12.2 on three PCs with KDE 3.5.9 and 3.5.10. This hardly makes be a bleeding edge user since KDE 4 releases have been out some time now, but I am operating on the basis of "if it ain't broke, don't fix it" principle. Sometime early in 2010 I am bound to move to Slackware 13.0 or 13.1 when that emerges with some version of KDE 4 on at least one of my machines.
Contributions to UserBase
I don't expect to be a major contributor to UserBase given my conservative approach to adoption of the latest and greatest, but where I see obvious gaps I will have a go.
Contributions so far: