[Relevant to my recent interests.][link] I bought an Arduino Uno this weekend and the amount of ideas I have right now are scary.
The primary benefit of this C library is that it will not trigger a reset on the board. This means you can stream data at intervals and not get a reset.
[link]: http://todbot.com/blog/2006/12/06/arduino-serial-c-code-to-talk-to-arduino/ “Arduino-serial: C code to talk to Arduino « todbot blog”