Peter
You have highlighted something which is a problem in the current MySQL trigger implementation. There are currently no show or information schema details for triggers. MySQL have said this will be addresses in future versions.
This is a problem becasue MYSQL limits you to a single trigger type per table so if you create one but forget the name there is no easy way to get rid of it.
My personal solution is to use a naming convention that will at least give you the option of removing the trigger. If you don't know the names then your only course of action would be to drop and recreate the table the trigger is on.
There is some discussion on my site about using a naming convention and solutions to the current problems, you can access the page here
http://mysql.gilfster.com/triggers/creating.php there is also plenty of other information on MySQL Triggers.
Andrew Gilfrin
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http://gilfster.blogspot.com
My MySQL related Blog
http://www.mysqldevelopment.com
MySQL Stored Procedure,Trigger, View.... (Just about most things these days) Information