I have many great landscape shots that got blown out with too much light in the sky portion.
Well if the sky is truly blown out, then you may be SOL... But if there is detail there there are a few things you can try:
1) The first is the shadow/highlight tool in PSCS -- just tweak the highlights down to where you want them.
2) You can make a layer copy, darken it so the sky looks good and then paint out the dark foreground to reveal the lighter image beneath with a big, soft, low flow history brush.
3) You can make a copy layer, grab the solid/transparent gradient tool, set the forground color to black for a ND effect, dark blue to match the sky for a graduated blue effect, or orange/pink for a warm graduated effect. Drag the graduate tool from the top down to about half way past the horizon -- experiment a bit with this to get it positioned where you want it -- then fade the opacity of that layer after the gradient to around 5% to 15% to emulate the SND or Split color grad look.