Here is a small list of wav sounds for your messaging software:
in the same series that the "you have got a mail"
http://www.ilovewavs.com/Events/GotMail/GotMail.htm
Here is a small set of files for instant messaging software:
http://www.ilovewavs.com/Events/IM/IM.htm
In french, 2 "vous avez un message":
here
Yes i know it is not a lot.