Linux Provides Some Unusual Network Devices

One of the main use of Linux is in networking, and Linux shines in this category, as noted before. Linux even offers some atypical kinds of network devices:

PLIP - use TCP/IP over your parallel port - great for networking a laptop.
SCSI - if you want high speed networking, there's just about nothing faster. Great for Beowulf supercomputers.
AX25 - TCP/IP over ham radio. Often used for automatic GPS position reporting.
Skin - Research on wearable computers and information transfer by skin contact uses Linux.

A single Linux box can use all of these network devices, as well as more traditional ones, and route between them. (Linux boxes make great routers, especially boxes considered obsolete by other operating systems.)

For more information, check out the Linux Networking Overview HOWTO.