Many aircraft are equipped with ACARS, this is I suppose to simplify as “Computerised Radio Teletype” which sends out short messages while in flight.
This ACARS listening station is located Birmingham UK,
http://acarsbhx.no-ip.info:8080 wait a few minuets and live transmissions should appear, use the search tab at the top of the page to interrogate the database.
List of other ACARS listening stations can be found at:
http://www.acarsd.org/webserver.htm
Caution: the law on receiving aircraft radio transmissions varies from country to country so be careful, particularly if you live in Greece.
BB