In .NET 2.0 potresti sfruttare questa semplice funzione, che sfrutta ParamArray:
codice:
    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        Console.WriteLine(MyMin(10, 15, 9, 10, 18, 88, 6, 19, 18, 16, 15, 11, 0, 16, -8, 9))
    End Sub

    Private Function MyMin(ParamArray valori() As Integer) As Integer
        If valori.Length > 0 Then
            Dim m As Integer = valori(0)

            For i As Integer = 1 To valori.GetUpperBound(0)
                If valori(i) < m Then m = valori(i)
            Next

            Return m
        Else
            Return Nothing
        End If
    End Function
Nelle versioni più recenti del framework potresti sfruttare le estensioni di linq e scrivere:
codice:
    Private Function MyMin(ParamArray valori() As Integer) As Integer
        Return valori.Min
    End Function