I like the Windows XP feature of windows-clustering on the taskbar. You know, when the number of tasks grows, rather than making the icon on the taskbar smaller and smaller and smaller as the number of apps increases, it uses one icon on the taskbar for multiple running versions. I see this all the time on browser windows but XP does this if you have multiple versions of any app running.

Want to control number of multiple windows for app before XP clusters :

Hive: HKEY_CURRENT_USER
Key: Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
Name: TaskbarGroupSize
Type: REG_DWORD
Value: 2 the number of windows for each app on the screen before they are clustered together