I want something like... vocaroo.com
The user visits the website, click a button, audio is recorded and then it's saved. I think it must be done using flash player. But I don't know where to start with.
This is also very useful and interesting website. try it http://online-voice-recorder.com/
You should take a look at Media Capture via HTML (http://www.w3.org/TR/html-media-capture/).