My music taste is generally based around the electronic genres, but every now and then I come across something a bit more traditional which warms me to the core. This one by The Arcade Fire needs to be played loud, when you're feeling really glum and I reckon it'll help you out of whatever hole you're in..
The Arcade Fire - 'Neighbourhood #1 (Tunnels)'
download: http://www.mediafire.com/?ykjmzw3adza