The rubber bushings at the top of the strut towers on my car are cracked. Is this dangerous in itself? The tops of the towers themselves seem solid.

 

I've heard that the strut rod can punch through, put a hole in your hood, and leave you with totally messed up suspension, possibly causing a crash. I don't know what the probability of that happening is.

the labor to replace that plate with the rubber bushing is pretty much the same as installing new front struts, so it might be a good time to consider doing that. use only genuine volvo strut mounting plates, as the aftermarket ones are known to fail prematurely and leave you right where you are now.