Add possibility to make an item return simple string constant

Would it be possible that an item can return a simple string constant? Maybe the "calculate" item could be modified to allow this.

Currently this seems only possible with system.run[echo "<some string>"] or regex magic, but at least the system.run method doesn't work for hosts monitored via SNMP.

It would be quite useful for letting items fill inventory fields automagically, e.g. from a template.