Just a minor update to the existing macro, to determine if the current day is Friday, and to action the item for Monday rather than tomorrow

Code in full:
Sub Toodledo()
'Forward the selected email to Toodledo, updating the subject with the appropriate shortcuts and move to appropriate folder
On Error Resume Next

  Dim objMail As Outlook.MailItem
  Dim objItem As Outlook.MailItem

        Set objItem = GetCurrentItem()
  Set objMail = objItem.Forward

    Dim strWhenToAction
  objMail.To = "" 'my toodledo email address
  If (DatePart("w", Now) = vbFriday) Then
    strWhenToAction = "monday"
    strWhenToAction = "tomorrow"
  End If

    objMail.Subject = "Respond to " + objMail.Subject + " @@work #" + strWhenToAction + " *Actioned" 'Prefix with Respond to, and append context of @work, date of tomorrow, and folder of Actioned

    Call MoveMessageToFolder(objItem, "Actions") 'move it to my Actions folder

    'clean up
  Set objMail = Nothing
  Set objItem = Nothing

End Sub

Private Function GetCurrentItem() As Outlook.MailItem
'Taken from code sample provided at http://www.pcreview.co.uk/forums/thread-2798274.php
On Error Resume Next

    Dim objApp As Outlook.Application
  Set objApp = Application

    On Error Resume Next

    Select Case TypeName(objApp.ActiveWindow)
    Case "Explorer"
      Set GetCurrentItem = objApp.ActiveExplorer.Selection.Item(1)
    Case "Inspector"
      Set GetCurrentItem = objApp.ActiveInspector.CurrentItem
    Case Else
  End Select

    'clean up
  Set objApp = Nothing
End Function

Private Sub MoveMessageToFolder(objItem As Outlook.MailItem, ByVal sFolder As String)
'Loosely based on code found at http://verychewy.com/archive/2006/04/12/outlook-macro-to-move-an-email-to-fol...
On Error Resume Next

  Dim objFolder As Outlook.MAPIFolder
  Dim objInbox As Outlook.MAPIFolder
  Dim objNS As Outlook.NameSpace

  Set objNS = Application.GetNamespace("MAPI")
  Set objInbox = objNS.GetDefaultFolder(olFolderInbox)
  Set objFolder = objInbox.Folders(sFolder)

  If objFolder Is Nothing Then
    MsgBox "This folder doesn't exist!", vbOKOnly + vbExclamation, "INVALID FOLDER"
  End If

       objItem.Move objFolder

     'Clean up
  Set objFolder = Nothing
  Set objInbox = Nothing
  Set objNS = Nothing
End Sub

The previous post contains hints on signing macros etc