Reliability and process variability are serious issues for FPGAs in the future. Fortunately FPGAs have the ability to reconfigure in the field and at runtime, thus providing opportunities to overcome some of these issues. This paper provides the first comprehensive survey of fault detection methods and fault tolerance schemes specifically for FPGAs, with the goal of laying a strong foundation for future research in this field. All methods and schemes are qualitatively compared and some particularly promising approaches highlighted.