Is the preferred option for the fuelling of special powers, spells and what not, to use a pool of points? Can there be an effective alternative? Has there ever been? Or is a fixed stat that you might roll against too rigid and unrepresentative.

I like power points/spell points/mana points or whatever - at least, I do for abilities where there can conceivably be some reserve of 'magical energy' or fatigue.
Main other alternative is memorization; you have a list of powers you can each use once. Encounter powers in 4E are also similar to this.
 
IMNO using a stat for power points is fine, given the right stat scale.
 
The main criticism of power point systems I've seen is that PCs tend to use their most powerful abilities over and over. However in part I think penalties for pool depletion can slow down spamming the same power over and over, as does a fairly small point pool.
 
As far as other alternatives go, the gaming den likes to propose a "winds of fate" model as an alternative, where all powers are useable at-will but where allowed actions each round are rolled randomly (i.e. "this round you can select from row F"). Its claimed by its proponents to cut down on action paralysis and spamming, although detractors complain about the random action choosing.

Another other alternative is WFRP2's system of really dangerous consequences. If every time you cast a spell their is a chance of turning you head into silly putty, people use though abilities less.

A variant measure between this and a power pool is 'spells cost Hit Points'.

Quote from: Ghost Whistler;521991Can there be an effective alternative?

In Shadowrun, spell casting causes the magician damage (although you do get a will power roll to try to soak up the damage, rather than taking it).

In White Wolf's Mage (at least the edition of Mage that I've played), mages build up Paradox points, which can have various nasty effects as you add more of them.

I think running out of magic/psionics/whatever is a weird gamey artifact that doesn't fit with a lot of genre fiction about that stuff.

More sensible "balancers" would be:
concentration (you can only do so much at once)
long casting times
interruption (either while casting or ending concentration)
spell failure
spells that backfire or hurt the caster

That's just off the top of my head. Also, consider that not everything even needs a cost. Something no stronger than a basic attack, or maybe prestidigitation-type effects, could just be free.

Of course, a lot of this depends on the game. Attrition is a staple of D&D, but if you want to set a game apart or emulate a genre, it's worth exploring other options.

Cast from HP - or from another common reserve that non-magicians would use for other things (willpower, luck, donuts).

Money (~ material components) - especially helpful to determine how magic affects economy.

Also there is merit to limiting the range of effects instead of availability. If all your magic is about transmitting messages to other mages that can be a huge asset, but won't solve all problems.