I appreciate this is an old forum post, but I came across it whilst reviewing open bug reports.
I don't know if you are still using SQL Monitor and if so are aware of the new Custom Metrics feature? It's purpose is exactly for this type of alert.
I had a quick play and came up with the following T-SQL that you can use in a custom metric which would then force an alert if a new DB was created.
WHEN create_date >= DATEADD(d, -1, GETDATE()) THEN 1
WHERE database_id = DB_ID()
If you create the custom metric and run it against "All User Databases" and then set up an alert if the value goes past "0" then this will alert for new databases created in the last day.
I appreciate this may not make sense if you haven't used the custom metrics feature, in which case I encourage you to check out the information on this feature in our support center.
http://www.red-gate.com/supportcenter/C ... 469829.htm
Hope that's of some help.