DSE-C is a project mainly written in C, it's free.
This is an *unofficial* little project designed to turn a DataSift augmented HTTP stream into a 'physical' light display using an embedded ARM board with FPGA DIOs and some huge LEDs
DataSift Embedded - C Componant
This is a really simple C program that uses libcurl to connect to the DataSift stream and then on and off a series of FPGA controlled LEDs based on Twitter user Klout scores.
Gareth / @NetworkString