Aaron Campbell recommended a site called Seeqpod which lets you search for your favorite mp3 files or music videos and put them on your blog. He tells how he used this in his own classroom.
Here are the instructions from the Seeqpod site for creating a playlist and adding it to your site. Here in blogspot you would use the resulting URL to "create a new element" under the Layout tab.
How do I make and save a playlist?
Quite easily. First, register (it's free and only requires an e-mail address and password), then search for some playable results. To make a playlist, simply press the green arrow that appears alongside a selected result, or drag a result to the player, then repeat. You can add as many results as you like. To save, simply click the Save button and title your playlist. At any time, using the nearby buttons, you can share and embed your playlists, as well as create new ones.
How do I edit a playlist?
To delete a result from an existing playlist, just press the red X that appears alongside it. If you'd like to change the order of results, simply click, and then drag, the result to your preferred placement.