Looks great, but... I can't seem to get any sound out of it? I click the Play button, and absolutely nothing happens.

It's disappointing, since I actually want to use it :p

Tried it in Chrome and Firefox 3 so far.

Small side note: log me in right after I register! Especially if you don't require email confirmation. It's a minor one-time irritation, but any friction you can remove, especially at the beginning of a user's experience, is worth it.