I am not sure hwat id the actual name of this type that I am thinking of, therefore I will describe the behavior.
Let's assume I have created a bunch of Items (events, blog posts, what ever)
I would like to be able to use these items in an items list much like the Relate Items but with a search autocomplete functionality. Very useful for large lists and also useful when trying to find a specific Item.
We have done something like that for one of our projects with it's a nightmare to replicate for all projects.
See below a video of the behavior. I am sure it can be improved even further
http://screencast.com/t/btyAkal5Y6H0
Thanks,
Adrian