Anyone have any house rules for a wizard casting a spell from his spell book?

[Havoc]

I do have rules, along with rationnalisation of the need to prepare.
http://enworld.cyberstreet.com/showthread.php?s=&threadid=25942

 

[Jürgen Hubert]

In our group, we allow wizards to cast spells from their spellbook. This still uses up a relevant spell slot, and takes up a minimum of ten minutes.

 

[Oni]

If I were to do this, i would say that they would have to perform a ten minute per spell level ritual and it would have to be powered b sacrificing an appropriate level prepared spell. Alternately for a caster that had no prepared spells I would consider 1d4 temp Con damage reasonable, the power for the spell has to come from somewhere (for those of a darker bend you could expand this idea to the ritual sacrifice of animals, or sentient beings for higher level spells).