It would be great if macro functions were permitted across a wider scope than just inside of trigger-based/problem-update notifications and expressions, map labels and graph names.

In this way, you could use item values inside of other items or as user macros.

For instance, I have a HTTP agent check which given some Basic Auth credentials returns a secret key. I would like to be able to use that secret key as the input to the value of a HTTP header in another HTTP agent check. Therefore I would like to be able to use a value like {{HOST.HOST}:MySecretKey.last()} as my input.

Allowing a wider scope of execution for these macro functions would achieve this, but I can imagine it would also open the doors for much more interesting things than just this.