The ubiquitous Baofeng UV-5R family can receive a lot of emergency services traffic depending on where you live.
Yep, love my Baofengs and Houston and my county EMS dispatches still broadcasts unencrypted on frequencies these radios pick up. I like the extended frequency range of SDR since I'm located near the Houston International Airport, assorted lifeflight hospitals, and a national guard airfield. On a good day there's even some offshore signals. I have a discone antenna set up for scanning a broad spectrum and there's always something interesting going on.
Good point about powering the SDR system. I forget people don't have as many solar electrons stored up as I do. My backup computer for the SDR system is a 13-yr old netbook (not even a full notebook computer) that handles things fine with low power requirements. My main, suped-up MacBook is an energy hog, though.
-Blast