The knowledge domain kinda sucks IMHO. The granted power is pretty weak since cleric are skill point poor and +1 level on most divintations is not often signifigant.Even if upped to +2 caster level, the domain power is kinda wimpy.
A few of the spells are 'dead weight' on the domain list except for the few times you need them in the average game and most can be gotten through the cleric spell list.
I swapped out the domain power with bardic knowledge and most of my players loved the idea.
KNOWLEDGE DOMAIN
Granted Power: Bardic Knowledge: A cleric with the knowledge domain may make a special knowledge check with a bonus equal to his cleric level + his Intelligence modifier to see whether he knows some relevant information about local notable people, legendary items, or noteworthy places. (If the cleric has 5 or more ranks in Knowledge (history), he gains a +2 bonus on this check.)
A successful bardic knowledge check will not reveal the powers of a magic item but may give a hint as to its general function. A cleric may not take 10 or take 20 on this check; this sort of knowledge is essentially random.
DC Type of Knowledge
10 Common, known by at least a substantial minority drinking; common legends of the local population.
20 Uncommon but available, known by only a few people legends.
25 Obscure, known by few, hard to come by.
30 Extremely obscure, known by very few, possibly forgotten by most who once knew it, possibly known only by those who don’t understand the significance of the knowledge.