"Challenging" Teaching Experiences for Math Grad Students? I am currently a graduate student, who will (hopefully!) graduate in the next year (or two . . .).  I have slowly come to realize that I enjoy teaching, and consequently want to do more of it!  My main reasons are:


to gain experience
to bolster my CV
to learn to be a better teacher


That last point is particularly important to me, because I feel I have received insufficient training in how to teach mathematics well.

Now, I have done the usual TA thing.  For the past year, I have also been an adjunct instructor at a local four-year college, so I pretty much know what it's like to be "fully responsible" for a course.  What I am looking for are challenging opportunities which allow me to do some–or all–of the following:


teach fairly sophisticated math to bright high school students / undergraduates
engage them in innovative thinking/research
be consistently mentored/evaluated throughout the duration of this experience


Again, the last point is rather important to me.  So my question is:


  Do such programs exist?


I am sure they do, but when Googling, I invariably come up with graduate summer schools, or "local" opportunities. (By "local" here, I mean those which are only eligible to students in that particular school's graduate program.) So I am hoping someone (or several people) here know more about it than Google does.

I know that most opportunities for this summer have probably already expired, but I want to stress I am not only focused on summer sessions.  In particular, I would gladly forego my usual TA appointment for a semester, to be a part of a more difficult and rewarding experience somewhere else.

Thanks in advance.

PS - This is my first question here, so feel free to edit my tags appropriately.
One possibility is to get involved with a program like Learning Unlimited (full disclosure: a few of my friends are heavily involved in running it). 

I've also heard (through the grapevine) that a short while back AoPS may be looking for instructors. I don't know whether the position is still/was ever available.