Bear in mind tablets are not PC; for instance the clipboard here just does not handle images, which means even apps capable to insert them afterwards like Smart Office will require you to import them through the (catastrophic) RIM file picker, for instance.
Originally Posted by new10
This said, the least unreasonable free diagram maker I found is called Scheme; I'm not sure you can save other than via screencopy but it indeed features automatic reeditable links for instance.
Then you have some drawing apps that do handle layers, geometric shapes and text overlays. Most of them are paying and I have almost no experience there; one that allows a free test drive is PaintBook, which is complex because rather a painting/retouch software to begin with, and in my experience it crashes quite often (other than that, has all you want including unlimited undo and impressive layer effects around shapes for instance).
You may wish to try the free DrawPad too, that has reasonable geometric shapes and undo levels.
Out of the flock very few have zoom capability, for instance, which I consider key, and very few are actual vectorial draw programs, which should be mandatory here.
Indeed if you find other, possibly paying apps I'll be very interested.
(edit) smart office also features some reasonable geometric shapes and arrows (not autoconnectable) in "powerpoint mode"