Something to think of in the near future. This and the dual serial port hack would allow me to run my router as a dedicated wardriving box. Please don't laugh if you see me driving down the road with a router on my dash.
This project is for people who would like to add a little storage to their Linksys WRT54G router besides the builtin 4MB flash ram. What we will do is connect an SD card reader to some of the GPIO pins of the CPU found inside the Linksys and with the help of a little driver we can use as a block device from Linux. This means that if you compile your kernel for the Linksys with e.g. support for MSDOS partitions and VFAT you will be able to mount, read, write, partition and so on your normal SD cards. The speed obtainable for reading and writing seems to be about 200 KB/s.