directory C:\Users\\AppData\Local\Skyrim the hidden file plugins.txt contains a complete list of all active plugins.
Yes, I've found plugins.txt to be quite handy for editing load order or exporting a list of installed mods, as I don't use any utilities other than the vanilla Skyrim launcher.
Also useful for testing specific mods, as you can make multiple backup copies of plugins.txt with alternate load orders and simply replace the text to add all your mods again.