I´ve been looking too, and this is what I found :
Por looks back to the roots, origins or causes of a thing, while
para looks forward to the result, aim, goal or destination.
POR is used to express:
Cause, reason, motive (usually to say why something has happened)
Lo hizo por rabia. (He did it out of anger.)
The period in which the action takes place:
Salieron por la noche. (They went out at night.)
The place where the action takes place:
Pasan por la calle. (They go along the street). Lo cogieron por los pies. (They took hold of him by his feet.)
The means:
Lo llamaron por teléfono. (They contacted him by telephone.)
Substitution, equivalence:
¿Podrías hacerlo por mi?. (Could you do it for me?) Por tres mill pesetas podíamos comer bastente bien. (For three thousand pesetas we could eat quite well.)
With verbs of movement
(ir y venir...)
Voy por pan. (I´m going for [some] bread.)
Expresses an action still to be performed:
La cocina está por limpiar. (The kitchen still needs to be cleaned.)
Expresses an action on the point of being performed:
Estaba por salir de casa. (He was on his way out of the house.)
With the verbs tener/dar to express opinion:
Le dieron por desaparecido. (They gave him up for lost.)
PARA is used to express:
Finality, destiny( often in sentences in the future):
Es para mi hija. (It´s for my daughter.)
Salimos para Suiza al finales de julio. (We´re leaving for Swiss at the end of July.)
Direction of movement, i.e `towards´:
Vienen para aqui. (They´re coming this way.)
Comparison:
Para lo que sirve puedes tirarlo a la basura. (For what it´s worth, throw it away.)
Convenience:
No es buena para la salud. (It´s not good for your health.)
Imminence: with estar + para + infinitive:
El jefe está para llegar. (The boss will be arriving soon.)
The examples are open to corrections....
