does anyone know where are they?

they don't exist. or they do, but they all suck. mp3 is a recording, and it's pretty much impossible to convert to instructions, which midi consists of, without some kind of advanced AI. ones that can, you know, drive a car through new york city by itself. best you can do is get a midi program and write it yourself.

I agree with Sinbios Zefiris Ark.

There are MP3 to midi converters, but all of them need payment in order to work. Some of them are trials, but only produce 15 seconds of sound.

I tried those myself, but found music to be unplayable, or odd in sound. I perfer you to make a midi yourself and try and remember all the notes played in the mp3. of course, this requires a skill of a good transcriber.

sigh* i want one

Here's what I use:

http://www.pluto.dti.ne.jp/~araki/amazingmidi/

But the MIDI files it produces are unplayable... if you pop them into an editor, all you'll see is a massive jumble of notes. You'll have to clean them up yourself-- that's the hard part :D :D