Just a quick tip for those who want to fit their Raspberry Pi into a small case,
SD cards installed in the Rapsberry Pi stick out a fair amount:

and frank26080115 over on the raspberry Pi forums has even soldered in an adaptor to use a microSD card: http://www.raspberrypi.org/phpBB3/viewtopic.php?f=45&t=9936

If you don’t want to get your soldering iron out, a simpler way is just to use an RSMMC card.
RS-MMC cards are available which are half sized SD cards which usually come with an adaptor to make them SD sized:

Installing an RS-MMC card in the Pi sits flush with the edge, and no longer sticks out:

Enjoy your new “slimmer” Pi !