Which types of spells can a Blinded caster still target as accurately as usual? Which ones require extra steps or give penalties because of blindness? Which ones can simply not be targeted at all, thus not cast?
Range: Personal or targeted at yourself
Has a Target entry
You must be able to see or touch the target, and you must specifically choose that target.
When blind, your only solution is to touch the target. If you are the target, this is automatic. Otherwise, the Invisibility entry of the Glossary provides an option when the location of a target is unknown:
A creature can grope about to find an invisible creature. A character can make a touch attack with his hands or a weapon into two adjacent 5-foot squares using a standard action. If an invisible target is in the designated area, there is a 50% miss chance on the touch attack. If successful, the groping character deals no damage but has successfully pinpointed the invisible creature's current location. If the invisible creature moves, its location, obviously, is once again unknown.
Also, a creature with a normal reach hitting you reveals its position:
If an invisible creature strikes a character, the character struck knows the location of the creature that struck him (until, of course, the invisible creature moves). The only exception is if the invisible creature has a reach greater than 5 feet. In this case, the struck character knows the general location of the creature but has not pinpointed the exact location.
This would allow you to target it with a regular Touch Attack, with the usual 50% miss chance for Total Concealment.
Ray spells are considered ranged attacks and allow trying to hit unseen targets:
As with a ranged weapon, you can fire into the dark or at an invisible creature and hope you hit something. You don't have to see the creature you're trying to hit, as you do with a targeted spell. The target will have Total Concealment and a 50% miss chance, though.
Creation or Summoning
Some spells create or summon things rather than affecting things that are already present.
You must designate the location where these things are to appear, either by seeing it or defining it.
As long as you can describe the location, you can cast the spell. As such, Summoning spells can be used when blind.
You do not need to see creatures to catch them within an Area spell. By default, you actually cannot pick which creatures are affected, just the area.
There is no indication that you need to see the point of origin of the spell:
you select the point where the spell originates
Burst, Emanation, or Spread: Most spells that affect an area function as a burst, an emanation, or a spread. In each case, you select the spell's point of origin
You must have a clear line of effect to the point of origin of any spell you cast.
You just "select" it, which I assume is the same as "designating a location" with creation and summoning spells.