One of the most exciting things to me in my first reading of the Savage Worlds book was the way cooperation was handled. The simplicity of the mechanic permits a GM to freely allow people to cooperate in any situation -- I'm not so sure I wouldn't allow people to cooperate in melee! The only thing that needed to be addressed (again, from my first reading) was the issue of arcane cooperation.
Many stories with arcane elements include arcane characters sharing power and melding their powers to do things they could not manage individually. Rarely do games modelling these worlds adequately address this story element. In the case of Savage Worlds, however, it is addressed by the cooperation rules, ommitting only one piece of information: what to do about power points.
House Rule
With the exclusion of Mad Scientists, when a character assists another character with an arcane skill roll, for each success and raise they may either:
Mad Scientists do not spend innate Power Points when they make their skill roll, so may assist each other according to the normal cooperation rules. The gizmo in question is tapped for Power Points normally.
Example: Colin is assisting Tracy with her Spellcasting roll. Tracy is casting Armor, which costs 2 power points, so the cost to Colin is 1 power point (regardless of the outcome). He chooses to add any points for successes and raises to Tracy's roll and declares this before he rolls. (This is essentially the same effect as is explained in the cooperation rules as written in the Savage Worlds rulebook.) He rolls and gets a success. This adds 1 to Tracy's result.
Example: Derek is assisting Susan with her Faith roll. Susan is casting Greater Healing, which costs 10 power points. Derek chooses to attempt to reduce the power point cost of the Miracle, which will cost him 5 power points. He rolls and gets a raise, which reduces Susan's cost to 8 points.
An Edge and perhaps a new power are suggested by this discussion, as well.
Power Edge
Power Gift
Requirements: AB, Seasoned, Spirit d8
A character with this Edge may give power points to another arcane character to support a power that character is activating. The two characters must be in physical contact in order for the power points to be passed. The character giving the power points must be on a held action when the acting character attempts to activate the power. Power points may not be passed between characters of differing arcane backgrounds. Power points are passed on a one-for-one basis.
The new power will be called Power Siphon. I haven't finished the writeup, but you can guess what it does from the name.