Recs.
Updated
SoundCloud is a busy sound sharing platform used mainly for music & podcasts. All tracks are streamable, and artists can mark them as downloadable or link to paid downloads elsewhere.
Everything is taggable, and it's easy to bump into music similar to or related to music you like.
SpecsUpdate
Pros
Pro Explore tab has new music constantly
Explore tab on SoundCloud shows trending music that can be filtered based on genre/tag. There's a constant stream of new music.
Pro Free to use
You don't even have to log in or sign up for an account if you don't want to.
There are paid options for if you want to upload large quantities of audio (eg if you're a music label you'll need this), but it's free to download as much and as often as you like.
Cons
Con Interface is full of bugs
The SoundCloud website has tons of problems, including issues with notifications, favorites, and uploading sounds.