I've currently taken a large liking to buying the Cartel Market companions as a bit of a companion collector myself, now I think this could be taken further by having "Dream Companions", mute versions of familiar NPCs we all love (Or hate).
I'm thinking a starting set of 10 will be a good start then more can be released with each cartel pack or event or whenever Bioware wish. These companions would be mute, have no conversations and for story sake, not be there. Just a decorative thing for role-players or people who want a certain NPC as a companion without having to get the voice actors in to record or write a story reason why.
HK-47 Revan Revan Reborn Thexan Vaylin Darth Marr Darth Jadus Satele Shan Darth Malgus Sargent Jaxo