Easiest way to verify the validity of a Clock Signal?

I've entered the stage of my current project where I need to generate and route various clock signals, sometimes within one particular IC, but often times between chips. I can read data sheets all day, and issue all the right register commands, but it's hard to troubleshoot (in general) when I can't be sure a particular clock is or isn't creating a problem. This frustration has led me to the following question:

What's the easiest way to verify the validity (frequency, quality, etc.) of a clock signal without the use of an oscilloscope?

Thanks very much for any assistance! -Dan