It is amazingly easy to open the EzTV668 RTLSDR USB dongle bought at DealExtreme: make a little pressure with a small flat screwdriver on both sides of the USB connector and the cover will pop up.
I wanted to check whether my dongle has the ESD protection diodes installed...
I was not surprised to find an empty U7 location next to the antenna connector. BAV99 should be the part missing, which costs next to nothing. Plus shipping, of course.