The SparkFun DEV-08544 is a creative way to connect various electronics onto clothing. 

This thread can carry current for power and signals. While not as conductive as traces on a printed circuit board (PCB), this thread makes wearable clothing 'wearable'!

This is a plated silver type thread (as opposed to stainless steel). This is a finer thread that can be used in standard sewing machines. Resistance is about 300 Ohms per foot. Spool contains 1 oz of thread, about 150 yards.

Product Sheet