I mainly serialize linked data through the Java Jena library. One of the features I really like is where you create a java class from an OWL file, which in eclipse enable autocomplete, when coding an open data serializer.
I would love to have the same autocomplete functionality in a simple editor. I often write triples in my preferred text editor Textmate, where I just type of copy/paste the long URIs. Having an editor that would autocomplete some preset prefixes would be really convenient.
Does it exist?