Save the following as a .vbs file and run it. It'll create a MappedDrives.txt in the folder the vbs file is run from. You can replace the strComptuer with another computer's name and get the list off of a remote computer as well.
strComputer = "."
Set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\cimv2")
Set objFSO = CreateObject("Scripting.FileSystemObject")
Set objOutFile = objFSO.CreateTextFile(".\MappedDrives.txt")
Set colDrives = objWMIService.ExecQuery _
("Select * From Win32_LogicalDisk Where DriveType = 4")
For Each objDrive in colDrives
objOutFile.WriteLine(objDrive.DeviceID & " (" & _
objDrive.ProviderName & ")")
Next
objOutFile.Close
HTH