When I write I have trouble listening to music with lyrics because I want to sing along and I can't write and sing! I tend to stop writing and just belt out a few verses. lol
If I need to be really productive I'll use BrainFM. I got a lifetime membership for a cheap price a while ago and I like it. It's different in that it just plays music with no words. They have music for focusing and relaxing and sleeping even. I only use the focus music since that's the only reason I'm listening.
I definitely use music to inspire some scenes in my books. I love trolling YouTube for great songs that are filled with angst to help me feel who my characters are going to be. Certain songs just speak to me. Tug at my heart.
While writing a story for Felice Steven's Kindle World launch I've been listening to a lot of songs:
Lost Boy by Ruth B
Unsteady by X Ambassadors
Hurts Like Hell by Fleuire
I Found by Amber Run
I just put them on loop with my headphones and listen to them over and over while writing painful, emotional scenes. It really works. It's like a soundtrack to my book.