SDR - Software Defined Radio

I just received my SDR tuner in the mail (2 day shipping on amazon).

Haven't had a chance to play with it yet (trying to finish an essay due tonight). But I have been watching videos on what you can do with SDR and it seems pretty cool. I plan to buy another one pretty soon so I can play with trunked radios.

All Public Safety radios in orange county are trunked (most law is encrypted) but I should be able to listen to Fire departments.

Anyone play with SDR and do anything fun with it?