Eric asked about independent study, and Jack mentioned physics ...
Since we don't have regular contact with a high-ranked jo teacher here in Minneapolis, I've been focusing a lot on fundamental 1-stick physics myself, and relying on a very mixed bag of tools.
For example, in juggling there's staff manipulation and staff spinning (see for example this dvd
http://www.dube.com/video/ArtStaffSageDVD.php). This art is a terrible postural influence but provides some great lessons in how the stick "wants" to behave. Also, whacking yourself with the stick over and over makes it less scary to risk somebody else doing so. 😉
The 9-pound "body bar" you can find in lots of gyms nowadays is about the same length as a jo, and just a little thicker. I've found it's also a good physics and ergonomics teacher. (And boy does that warmup sequence get more interesting.) (Be careful though, and work slowly, or you'll risk serious injury.)
There are some inspiring aikido weapons tutorials out there as well. I'm particularly fond of this video with Charles Koh:
http://www.youtube.com/watch?v=bPbBACWbu0U -- in terms of posture and application he's on a different planet than we are, but the way he transitions between fluidity and structure has given me a lot to think about.
My *hope* is that an honest relationship with the stick's own physics and good posture from aikido will keep my jyodo correct enough to be improvable later, rather than needing to unlearn and relearn the whole business. I certainly find it improves my aikido, and I find that over time the jyodo material makes more and more sense; but who knows if my understandings are correct...