March, 2001. Wincustomize.com went live.
This week marks One Quarter Of A Century that Stardock has hosted the longest-lasting Community-oriented skinning site and related Forums.
I remember getting the message while on Skinz.org to log into Wincustomize and create an account, so I did.
The first 20 User IDs were reserved for Stardock themselves so my User ID of '23' gives a good indicator I was day one. Somewhere along the line I was 'assimilated' into the machine and am still here.
OS Graphic User Interface Skinning has evolved with the evolution of the Windows OS. At the beginning it was relatively straight forward and 'simple' and attracted a huge following, however a dozen or so years into the life of skinning things became a little more difficult to achieve and the excitement waned somewhat.
I highly doubt that the concept of 'Customizing' will ever disappear, particularly as the Windows OS takes some odd detours of functionality. Stardock's current successes with both Fences and Start 10/11 in particular, along with the original stalwarts like Windowblinds, and others demonstrates where there's a need there will always be a Better Solution. 
Wincustomize.com was [and still is] Frogboy's "baby". Without his vision, seeing the need for a stable/reliable site for GUI Modding we all would not be here at all.
Thank you, Brad [and the crew with the spanners that keep it alive].