OFM,
Here is a good place to check out different stakes.
I've been using
Simon Metal's titanium tent stakes for some time now. Because they are titanium, they will take a good deal of hammering without bending. And because they are thin, they are easier to drive into the hard rocky ground. Of course, because they are thin, they also don't necessarily stay fixed in looser soil, but placing rocks on top will get the job done.
I've also used the rock only method where you tie off a piece of chord to your corner tent loops and tie a fist-sized rock to the other end and then place a larger rock over the chord. This works well too...especially in places where the whole ground is rock and it's impossible to drive stakes.
AC