I asked the subreddit about possible practical uses of tulpas, and was told that
A tulpa should be made for companionship, not for their practical abilities. They are sentient beings, not tools to be used for your benefit.
That sounds like a very practical use to me. Many people are lonely. (I remember reading one thing where wasn't there a guy making a tulpa of MLP's Twilight Sparkle?)
Thus spake Eliezer:
It seems that many here might have outlandish ideas for ways of improving our lives. For instance, a recent post advocated installing really bright lights as a way to boost alertness and productivity. We should not adopt such hacks into our dogma until we're pretty sure they work; however, one way of knowing whether a crazy idea works is to try implementing it, and you may have more ideas than you're planning to implement.
So: please post all such lifehack ideas! Even if you haven't tried them, even if they seem unlikely to work. Post them separately, unless some other way would be more appropriate. If you've tried some idea and it hasn't worked, it would be useful to post that too.