I have a house that is 5 years old and the OSB floors make a cracking noise (like stepping on straw). Other than ripping out the flooring, any suggestions on what can be done?

It's very probable that the builder didn't use subfloor construction adhesive in that area. The best way to approach this problem is to go into your crawl space or basement, remove the insulation from the area where the noise is coming from and place wood shims with construction adhesive in the gap that's there. The other option is to pull up the flooring and drive screws into the OSB and into the floor joists, of course this is labor intensive and if you're paying someone else can be quite expensive.

Why is every one switching to osb for subfloors? Just wondering. Anyway in Texas we use 1 1/4 tongue &groove plywood with liquid nail &screws.

OSb, like plywood, is an engineered wood product that is constructed to have the same characteristics or better as plywood.

The difference, at least until recently, was that OSB could cost 5x less than plywood.

Since the Iraq war, OSB has remained cheaper than plywood but only by a few dollars.

But at $10 per sheet difference than plywood on average, OSB makes its use more economically attractive as time goes by....and it will likley replace plywood for floors and sheathing just as plywood replaced dimensional lumber for use in floors and sheathing.

If the joists are open below look under the floor and have someone walk above to see what the cause is. If you can't see because the ceiling below is finished you can try a product sold at most home stores that screws the subfooring down thru the existing carpeting or wood.
It comes with special screws and a guide to get the screws to the precise depth. The screws are long and made so the heads and top of the shaft snap off slightly below the floor level leaving the threads holding the subfloor and joists together with only a tiny bit of the shaft visible. In carpet this product is invisible, in other flooring materials you'll have to be creative to cover up the shaft. Look them up at Squeeky-floors.com