Custom ToolParts can be really useful when you need to say select an item froma dropdown list whose data is stored in a WebService.  Thats how I’ve useed them before.

But Consider using them for more than that.  I created a new one, it has no properties to update or show, it just displays the Version number of the Assembly and the current user viewing the properties.  Im going to extend it to display a host of other useful support information