Soundcloud.com is good for lots of reasons. Here are two:
1. You upload a sound file to it and you can then share it via facebook etc. But what I'm interested in is that you can embed it into a blog page (see below) or any other web page (e.g. a Moodle web page, book or label) and you get a built in player.
2. You, or others, can tag the file with a text comment at any point along its timeline. That's great! And it's dead easy too. Here's a quick and uninspired(!) example: