We have some Mac Minis in our server room and I forgot the VNC password.
I could connect physically to the machine but I needed a DVI monitor and I did not have one :(
Answer:
Connect thru putty.exe and use this excellent command:
sudo /System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/Resources/kickstart -activate -configure -access -on -clientopts -setvnclegacy -vnclegacy yes -clientopts -setvncpw -vncpw mypasswd -restart -agent -privs -all