There is a widget that allows you to combine widgets into a 1x1 square, called WidgetFolder. Unfortunately, it's not as sleek as even the standard folders, as clicking on it doesn't slide out a pop-up with the contained widgets (or files, apps, contacts etc), but opens up a separate screen where you can open, arrange and add widgets (or other folder items). Opening up that screen takes a good one or two seconds, which can become quite frustrating in the long run. It also crashes to force close every now and then, especially when you're arranging or deleting icons from it. But so far it's the only one I've found. Sadly, it's definitely not good enough for me to stop looking.