meteorstrike, lightning bolt, and if a monster is immune to both--deadly discs! Elemental strike for mass carnage. Divine death makes short work of imps and stone gargys. Also obsoletes freeze.
I agree, summoning spells are worthless.
But then, I'd rather blow stuff up <img src="/ubbthreads/images/graemlins/badsmile2.gif" alt="" /> <img src="/ubbthreads/images/graemlins/mage.gif" alt="" />