For mages, I allow the Cast and Blast optional rule from
http://ottgaming.grimoire.ca/Spell_Changes for missile and melee spells. (Basically, you can cast the spell as a free action once you're done Concentrating, rather than having to wait another turn.)
Missile spells mostly suck because of casting time. The one time they're pretty good is when you charge one up outside battle and carry it around. The Cast and Blast rule doesn't make that case any better, but it makes actually casting missile spells during combat more reasonable.