Piezoelectric sensor

I bought 2 piezoelectric sensors from sparkfun: http://www.sparkfun.com/products/9196 I'm currently using them for something else, but I was wondering if I could use them as actuators, microphones, or speakers?

I was just looking through some of the cool applications listed at the bottom of this piezo film doc: http://resenv.media.mit.edu/classes/MAS836/Readings/MSI-techman.pdf some seem a little far-fetched for these but microphone, speaker, why not? Or do they need some kind of raw film, without a plastic laminate?

Thanks!

Or do they need some kind of raw film, without a plastic laminate?

No but they do need a considerable amount of amplification before the output is anything useful you can use in an arduino.

Yes you can use the as a microphone but they are not very sensitive and there are better alternatives.