Magic houserules?

So while I overall really enjoy the Dresden Files RPG (both GM'ing a game and participating in one), I run into the problem of Wizard characters becoming almost absurdly powerful.

To whit, one of my players currently plays a pyromancer who, with a dinky nine refresh, is able to throw nine-shift fire spells around, which makes mincemeat of quite a few nasties that would otherwise be a credible threat. And I don't just want to thow bigger monsters at them just to make something a threat to him because then everyone else feels like they're not contributing.

Do you have any houserules that make magic just a little bit more managable?