I browsed around the tulpa community some more, and found some mentions of "servitors", which have the same mental recall abilities (and apparently better access to current information - some people there claim to have made "status bars" projected on top of their vision), but the community doesn't consider them sentient. This forum has had several conversations about them. The people there tend to (badly) apply AI ideas to servitors, but that might just be an aesthetic choice.
This would probably be a better munchkin option, since it has most of the same usefulness as a tulpa, but much less likely to be sentient. Supposedly they have a tendency to become able to pass the turing test by accident, which is a little worrying, but that could be the human tendency to personify everything.
In general, what I'm taking away from this is that intense visualizing can have really weird results, including hallucinations, and conscious access to information that's usually hidden from you. I don't have a high degree of certainty about that, though, because of the source.
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.