Hello:
I was thinking that a great ability to have as a caster would be to 'mass' any spell you have as a metamagic feat. It would allow for faster buffing (at a cost) and would seem to improve the game.
Some random thoughts:
1. It could be a feat, like the other metamagics since it is valuable. However, it could be an enhancement as well, depends on the final numbers.
2. It could only apply to buff-type spells applied to the party, rather then offensive spells in order to limit it.
3. It would surely have to cost significantly more SP since it's on the whole party, but less then simply 12x the base SP cost of the spell to allow a caster to benefit from taking the feat. Possibly 4x the SP to recognize it being used on a 6 member party (RAID's could just get the benefit of scale).
4. Should be able to turn it on and off like other metamagics.
Those are my quick and dirty notes on it.
I would love to see it in the game some day.