They may be just for fun. If you had a robot that understood you, could hold a conversation with you about your interests, and even had goals of its own (good or bad), it wouldn't really need to do anything special. People would buy it like it was a toy or game.
Also, they might be usable as programmers, artists, designers, anything creative that a computer can't successfully do on its own.
It really just depends on what you define as 'consciousness'. Does it just understand what it's supposed to do, decide if it wants to, and if so, complete the task? Or does it wonder about religion, politics, moral situations, etc. that even regular humans don't fully understand? If it was pretty much just a human, it wouldn't be any more useful than one. Of course unless it can solve problems super quickly and effectively, then it would just be a really good worker.