The police scanner apps are good for L-rides. But be aware that you can't actually scan for nearby frequencies, there are set feeds that you choose from, and it's not guaranteed that your town/city will be on there. They just stream live feeds from the internet. I was a little disappointed because I got the 5-0 radio one and it said you can add custom feeds, but apparently my county doesn't do live internet feeds. So all in all it's useful if you live in a big city but it's better to just have a real police radio that will scan (I have one of those too but it'd be nice to just have it in my phone).
Not sure if someone posted this yet but... Spawn HD is super dope. Not the free version the real one. If you have it PM me for my settings and you will not be disappointed...