This plasmoids lets you group other plasmoids.

To use it simply put it on the desktop or panel, then drop other
plasmoids from the add plasmoids dialog or drop an icon from kickoff.
The plasmoids will be ordered in a grid.
If you put it in a panel you can choose if you want it to stay as it
is in the desktop or in a popup that you'll be able to open
clicking on a icon.