As I love couch gaming, many of my games have a local multiplayer option.
For long time it was split screen gaming (for many of my XBLIG games).
But for my new engine, I'm doing it another way.
All player are on a single screen and a small part is reserved for each player interface.
It works pretty well for basic games like "little bastard" with only 3 interactions. (each button mouse is an interaction) and no resources.
But for bigger game like "little Kingdom 2" with several resources and lot of interactions, it's a problem, I can hardly put 23 buttons in my tiny interface...
Even if it was possible, it's hard for the player with a pad to go in the corner for each interactions.
So I'm using this circular contexual menu.
Each time you want to interact, a circular menu is displayed near the cursor with the possible interactions and some expanation. It disapear when you've finished.
It doesn't take a lot of place, and you don't have to move the cursor a lot.
So the game is playable even if 4 player games. And the interaction speed is nearly the same for the mouse player than for the pad player.
In LK2, I'm using 3 distinct circular menu and it work pretty well!
It's so usefull, that I may be able to make bigger game using this system (One day, I will make a 4X).