In-Page & Instant Media Player – Yahoo! WebPlayer
Yahoo! WebPlayer is a fresh web-based media player from Yahoo! which can be integrated into any web page with just inserting a line of JS code.
It has support for many media formats including MP3, WMA, YouTube, Yahoo! Video, etc. and works automatically by scanning the related links/files in a web page and inserting a "play" button besides each of them.
Once the "play" button is clicked, an in-page (can be a good way to keep the users in the same page) and good-looking player appears with a nice slide effect that plays the media either in a tiny audio player or a video player.
The player can even detect related media itself and link to them if the "term detection" mode is enabled.
The API for the player is under development and it'll offer much more flexibility once launched.
P.S. You'll remember the popular Yahoo! Media Player, WebPlayer is actually the next-generation of this product.