The current list of media types is fantastic but the ability to POST alert content to third party HTTP/S APIs would be a fantastic addition.
For complex scripts that broker between external ticketing systems, etc. this would enable "scripts" to run as daemons and listen for simple RESTful style requests from Zabbix and process them concurrently, without Zabbix causing a fork. Or simple POST requests could be entered directly in a NoSQL DB or message bus that support HTTP methods.
I see this working with a new Media Type called "HTTP/S API" with the following options:
URL: The HTTP end point
Expected response code: numeric (201, 202, nil, etc.)
The body of the request should include the standard fields, title, description and contact (and macros?? please!