i really don't see mages as too weak, i think a few changes that would be very welcomed would be somthing like evasion not working in anything but light armour or robes as it should only work. that would make reflex spells actually useful. and definatly GMW and holy sword need to be nerfed.
i can still beat pretty much anyone though with a simple extended bigbies then i have my way with him for about 8 rounds

it just takes tactics for mages to win a fight, can't just blast away at somone and hope to win. because once they're close.. it's dangerous. i myself plan to take a monk level once i get 21 for evasion and ofcourse dicipline, at which point i won't fear knockdown very much (+7 diciplien gloves, two +5 dicipline rings) = 24+17+2 = 43 dicipline.. not bad.
as for clerics, take away the extra attack on DP and just make it give fighter AB, not BAB, and then perhaps make it not stack with divine favor. and ofcourse GMW needs to be nerfed, perhaps duration on darkfire upped (however leave flame weapon alone, why? because it only benifits teamwork, there are no mages out there actually using this spell on themselves) and maybe a few more nerfs on clerics like magical vestiment only being 1/5 levels.. perhaps that same formula for GMW, capping at +4 for both (level 20).
then make spells like firestorm full PvP, perhaps flamestrike too, storm of vengence too. mages have to be cautious wiht thier area of effect spell, why not the cleric?