The varient datatype equivlent in VB.NET is Object.

Here's a sample:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim MyVar as Object
MyVar = "Hello"
MyVar = 10 + 10
MyVar += 50
MyVar = New FileStream("c:\test.txt", FileMode.Open)
MyVar = Nothing
End Sub

You can set basically anything to it :-). I don't reccomend using this type often, it takes lots of memory.

Also, you may want to set your variable equal to nothing when your finished with it, just in case the GC dosen't get to it fast enough.