I use the med. chamelion purse insert. I keep it filled and just lift it from one purse to the other. It is lightweight, makes changing purses easy and it has a ton of pockets and compartments (omg, I sound like a commercial....). I think the one I have is the extra sturdy but they have a website where can you can look at the different models.
I use the Damier Mini Accessories pouch ... it's perfect for those little miscellaneous things. I posted pics in one of the threads once of how much I could fit into it ... it's holds a lot and yet doesn't seem overly large.