Even when really pushing my Mini 9 it only gets slightly warmer than usual.
My first thought was to prop up the front and allow greater airflow to the bottom vents, but then I realized that the heat sink for the CPU and chipset is that aluminum panel beneath the keyboard and that it wasn't making any real difference.
I've also noticed a ton of stickers inside these things, like underneath the mini PCIe slots. (I have a pretty good idea what goes where at this point.)
I know circuit boards are not heat sinks necessarily, but I removed all of them from within mine anyway just to reduce any insulating effects. One or two were curling up at the corners also, which will definitely impede air flow.
Every little bit helps.
Inspiron Duo: Win7 Pro 32-Bit, Intel 6200 Wifi Upgrade
Former Inspiron Mini 9 Owner, Modder, Enthusiast