Why not use an ALT tag?
This is an excellent example of how we do NOT want to see HTTP
progressing, such that clients say things they don't really mean and
servers try to read clients' minds. A client should not send */*
unless it really means it, and a server should take it at face value.
This is supposed to be data transfer, not artificial intelligence.
-- Marc VanHeyningen <http://www.cs.indiana.edu/hyplan/mvanheyn.html>