I'd appreciate some recommendations on the best way to approach this
simple(?) VBA task. I'm new to vba, but familiar with perl, and miss
the easy use of associative arrays.

I want to create a structure like this:

<key1> = item1, item2, ...
<key2> = itema, itemb, ....

I don't know in advance how many keys I need or how many items will be
in each list. The example below doesn't work, but gives an idea of
what i'm thinking of. TopList is a collection of collections. If a new
key is found, then I want to add a new item (a new collection
object)to TopList, and then I want to add items to that sublist. This
is pretty easy to do in Perl, I'm sure there's an easy way to do it in
VB as well... Then I would like to list all the collections and their
contents of TopList

Sub test()

Dim TopList  As New Collection
Dim i, j As Integer

For i = 1 To 4
    For j = 1 To 3
        If TopList.Item(i) Is Nothing Then ' how do i test to see if
the collection exists?
            TopList.Add Item:=New Collection, Key:=i
        End If
        TopList.Item(i).Add j ' is this how i would add an entry to
the sublist?
    Next
Next

End Sub