I like to build intrinsic sensors with fabric because they are more flexible and survive washing and environmental stresses better than extrinsic modules such as those in the Lilypad ecosystem.
Combinations of piezoresistive, resistive and conductive textiles and materials can be used to make an amazing number of different sensors and there are still plenty yet to be invented. You can find plenty of examples of these in this blog and Hannah Perner Wilson's blogs and instructables postings. There are also nice case studies on materials supplier sites such as these from Eeonyx:
Here are some of my favorite materials for sensor building: