This post talked about different ways to find music but now I'm gonna go for a few specific apps (computer or phone) that I tend to use a lot for various reasons.
We'll start off with my newest discovery - Coffitivity. I was scrolling through Tumblr (surprise) and found a link to this in a "life hack" masterpost and decided to give it a go. Basically it provides the noise of a coffee shop to either play on it's own or layered with your own music. It's brilliant and the many good things about it are outlined on their website and probably on the app store too. It's free, by the way so don't worry about that. For me especially, I need background noise at all times and I'm usually home alone so this is so cool.
Another app that goes along with the last is 8tracks. I know I mention this a lot but I really use it so often. There is a mix on there for everything. In the shower I listen to an upbeat playlist and then getting out I switch to a more mellow one instead of turning my computer on and searching through iTunes for ages. The playlist I'm listening to today sounds amazing with the coffee shop noise in the background. I have an 8tracks account and try to post a playlist every week so here's a shameless promo for that.
BandsInTown keeps you up to date with concerts in your area, you can set favourites and it can connect to your Facebook to scour your liked artists too. It also gives you recommendations and ticket links. It's a lot like the Live Nation app but if you have the space for it, I'd download both.
Another app that isn't specifically music related is Countdown+ though I have no preference for countdown apps and I just chose the simplest free one. This one notifies you updates on approaching events on your lock screen like "such and such is in 30 days". I usually have a bunch of concerts upcoming and having them all in one place with the venue, date and all that is helpful to keep myself organised.
I mostly made this post because I was so hyped about Coffitivity but I wholeheartedly enjoy all of these apps. Shout @ me if you have some other cool findings!