ed (which is the more frugal, older brother of vi/vim) might indeed be a bit under-hyped. Which advantages does it have for you?
Funny thing a while ago I had a small side-project for a data collection task in my PDA - a kind of minimal database to record daily stuff. So, a PDA has limited screen space and typing speed, and I tried to make the UI with as little typing as possible. And then it dawned to me that I was essentially replicating ed's interface!