Back in 2009, I published Convert CSV files to Excel, a vbscript which converts csv files to xlsx format. Although there is not good way to directly support drag and drop with PowerShell, it can be done with a form. Convert-DroppedCSVsToExcel.ps1 was mostly written as an exercise for me to work with drag and drop in PowerShell. It contains both a ConvertTo-Excel advanced function and Get-DragAndDrop, which demonstrates how to get the full path name of a file dropped into a Windows Form. The script autosizes the resulting file and you select a maximum column width.