Imports System.Text.RegularExpressions
' ...
Dim pattern As String = "(?<Protocol>\w+):\/\/(?<Domain>[\w.]+\/?)\S*(?x)"
Dim reg As Regex = New Regex(pattern, RegexOptions.IgnoreCase Or _ 
  								          RegexOptions.Multiline Or _ 
									  RegexOptions.IgnorePatternWhitespace Or _ 
									  RegexOptions.Compiled )
For Each m As Match In reg.Matches(Me.RichTextBox.Text)
  Me.Listbox.Items.Add (m.ToString())
Next