something like this

vb Code:
  1. Private Sub PictureBox_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PictureBox1.Click, PictureBox2.Click, PictureBox3.Click
  2.         For index As Integer = 0 To FlowLayoutPanel1.Controls.Count - 1
  3.             If TypeOf FlowLayoutPanel1.Controls(index) Is PictureBox Then
  4.                 If sender.Name = FlowLayoutPanel1.Controls(index).Name Then
  5.                     MessageBox.Show(index)
  6.                 End If
  7.             End If
  8.         Next
  9.     End Sub

the typeof line is actually unnecessary in this case, but i like it there