Sending a paper to a conference with indicating that it is a preliminary version
In my field (one of the social sciences), where conference papers are usually regarded as work in progress that at a later stage will be send to a journal (as opposed to computer science, where 'publication in a conference' often is the goal), it is not uncommon that people include a statement like "Work in progress, please request most recent version from the authors before citing". I've done that several times, in fact.