I think really what it boils down to is how people perceive themselves. Originally there were just Jedi. But keep in mind what we really have are a bunch of people sitting down to computers and looking into this path on websites. So thus as people made attempts to follow or construct a “Jedi” path, they soon found that accomplishing the example set forth by the fictional Jedi characters was not quite as easy as it might seem at first. So then as people noticed the difference between themselves and the fictional Jedi, they began to try to find ways in which they fit into the picture. Then there are also things in the book fiction that enter in too. So really, I think it’s a matter of how people perceive themselves in comparison to what they’ve seen.
I pretty much agree with Andy’s list – but for the “service”.
I believe a Jedi is not a free-standing charitable/guardian. But rather is called upon the Force when the Jedi’s service is needed.
Our learning and training are to be able to respond when called upon – and most often that is in situations where we have to step outside the human herd and possibly be less-liked to protect or defend.
Sometimes that means doing nothing when everyone else is doing something harmful – but not deadly.
What I took from the films that most influence me even now is that the Jedi were tolerant of others, were mindful, but waited until they acted out of an instinct and within the Force.
I’ve been thinking on this subject a bit myself lately, and I’d have to say the ideas presented here make a good spiritual or religious person… but do they make a Jedi? What separates a Jedi from a good Christian, Muslim, or Buddhist? I’m thinking Star Wars or Jedi philosophy (i.e. the Code) would fill in nicely as a fourth requirement. This is what makes us uniquely Jedi. It’s where the name comes from, after all.