I recently installed and used a miniature Sanav MK-7 GPS logger from SparkFun. This device is really small: a little smaller than one AA battery. I wanted to use it with Apple's OS X Leopard operating system: here's how.
The MK-7 is built around the MTK datalogger chipset and the Transystem EB-230 GPS engine, and includes Flash memory for storing GPS logs. It is connected to a computer with a USB-like cable to either charge the embedded battery, or to upload a data log. Like several other embedded devices there days, the Sanav actually uses a TTL-level serial (RS232) protocol, and needs a GPS-to-serial converter. This is embedded in the cable so that although the whole the cable looks like USB-to-mini-USB, it's actually got a chip inside it that converts USB signals to RS232, put uses a mini-USB connector on the logger to achieve the RS232 and power connection.
The means that to communicate with the device, you need to have the correct USB drivers. The cable I got with my device uses the Prolific Technology Inc. PL-2303 USB-to-serial bridge chip (0x067b), and the drivers for just about any operating system including OSX can be found here:
Once the driver is installed, connecting to the serial port lets you see the live data logging (use a baud rate of 115200):
screen /dev/tty.usbserial 115200
My MK-7 seems to run a firmwre suite called M-core_2.02.
To extract logs, one option is to use the Java-based software package BT747 available from: http://bt747.free.fr. Be sure to load the version that includes "RxTx" libraries. You can also find it at the Sourceforge link http://bt747.wiki.sourceforge.net/mac_installation