I don't think you can compare RoR with ASP.NET given that the whole .NET framework (and almost every Managed API) is available to you. To my knowledge, RoR doesn't have anything like CreateObject/GetObject.
In RoR you have the whole Ruby framework and all standard and third-party libraries available to you...
I'm not actually sure which CreateObject/GetObject you are referring to as I don't do ASP.NET (so I am not arguing in any direction, just offering a Ruby / Rails perspective), but if it has something to do with OLE objects you could do this in your Rails app:
excel = WIN32OLE.new('excel.application')
workbook = excel.Workbooks.Add()
excel.Range("a1")['Value'] = 42
...and then serve the fantastic budget spreadsheet back to the user.
Note that I made a wild guess about what CreateObject and GetObject actually is - so please feel free to enlighten me .