Yes, I've used English Central, partly owned by Google Venture, with groups of students. It's very similar to Tell Me More and Talk to Me by Auralog.
I had a look at your quickie MP3 project. It looks good and it seems to be similar to the NanoGong standalone applet that's used in the audio assignment type for Moodle 1.9. I've been working on something similar too but with Flash. It:
- Records user's mic in WAV format.
- Users can also submit text alongside the audio.
- The audio gets saved in the course files directory with the user's name as the file name.
- A link to the audio file and any submitted text is saved as an entry in Moodle's grade book.
- Sends the data as a byte array so a PHP service script writes it to the appropriate MIME type(s).
- Circumvents php.ini and Moodle file size limits.
Some, but not all browsers, can play WAV files natively, and modified Flash apps can play them. I'm not a low-level programmer (they're rare and special people!) so I have to rely on 3rd party libraries for encoding binary data such as audio. All the Flash CODECs I've tried either struggle or crash when trying to encode WAV to MP3 (Flash Player doesn't do multi-threading) and it's not really acceptable from a user's point of view. I think most people use Java applets just because they have better developed and optimised CODECs. Adobe Alchemy (optimisation engine) looks promising but I think the main problem is transcoding from WAV to MP3. I'm sure there must be a better solution and I've shelved the project for the moment.
To get an idea of how it works in principle, it's similar to this app (open source) that I developed, which is for drawing concept maps: http://blog.matbury.com/2011/06/19/students-can-save-snapshot-images-on-moodle/