Creating a custom control which contans user controls

[Nils]

I need to create a custom control which contains both default user
controls and any other html or control the developer uses in between
start and end tags.

The final result should be able to do this on the ASPX page (or within
another control for that matter):

<CustomControl:myControl runat="server" id="whatever">
<!-- html goes here -->
blah blah blah

<!-- plus any other controls the developer chooses to add to the
control.....-->
<aspataGrid runat="server" id="DataGrid"></aspataGrid>

</CustomControl:myControl>

Does anybody have any ideas on how to accomplish this?