Kind of stupid, but I forgotten what I used Pluggy for. Maybe it was for Journal Mod that I don't use anymore. So, apart from the mods that require Pluggy and are listed on the Nexus here uder Required section: http://www.nexusmods.com/oblivion/mods/23979/?

do you know of any other mod that require Pluggy?

If you want to back up your map settings, then Map Marker Overhaul uses Pluggy. It's optional though.

You can also use Pluggy to use another pricing list in Enhanced Economy. You just need to install it long enough to change the prices, then you can remove it again. That's what I use it for.