[jacquesm]

Ok, an even better one:

http://imgur.com/a/FXhbH

[ythn]

You could make the one on the left even taller by tilting the yellow rectangle so it also utilizes the hypotenuse

[ErikHuisman]

now do one with the top piece upside down (or put that piece on the bottom)

[jacquesm]

I tried, it will not balance (nor at the bottom, because COG is off-center too far from the center of the round 1x1 plate for it to be able to stand on its own).

I'd love for someone to beat this one.