Our DM is currently considering using the Spell Points system but, at the moment, we're only using the Magic Rating rules. These should really be Core, as far as I'm concerned; I've been using them ever since someone on these very boards suggested exactly this mechanic a couple of years ago.
Oh, and we're also using the 3/day Metamagic thingummy -- but no-one's actually got any metamagic feats... The thought is, maybe this change will inspire someone to finally pick one; in 3+ years, only one spellcaster in our group has ever had one of those feats: my old abjurer with Extend Spell. We've always considered them too expensive for their benefits, both in feats spent and higher spell slots required. Using 3/day without added level slots sounds much more appealing. My new druid is considering Reach Spell or Extend Spell, except they're vying for position against other goodies like Spirited Charge and Weapon Focus: Lance (he's a knight chevalier and his animal companion is his warhorse).