Firefox, specially the Linux version, and many other browsers are unable to play background MIDI files. This simple applet lets you add background MIDI to your webpage and allow every Java-enabled browser to play it. It only has two controls but that's all you need to play, pause, seek and repeat.
To use, save the JAR file and add the code below to your web page. The name of the midi file is required.
<APPLET codebase="." code="MiniMidi.class" archive="jar/minimidi.jar"
width=300 height=30>
<PARAM NAME="file" VALUE="filename.mid">
</APPLET>
The source code can be extracted from the JAR file.