There are some slightly uglier but cheaper alternatives for Raspberry Pi users that want a lower-profile SD card. They might be too thick for a Mac's SD slot though.
There's a $12 version on Kickstarter now:
http://www.kickstarter.com/projects/443556734/pio-microsd-ad...
Adafruit will also offer a similar one soon: http://www.adafruit.com/products/966