The olm is the only species in the genus Proteus within the Proteidae family (the other genus is Necturus). Olms are cave salamanders found in Southern Europe. Like many other derived groups of salamanders the males courts the females before depositing a spermatophore for her to pick up with her cloaca. Fertilization is internal in the olm.
In addition, there is a recognized subspecies that is black in color and has more developed eyes.
Finally, olms are supercool because they represent an anomaly within amphibians in the relationship of size to longevity. A paper in 2010 (link here) suggested the olm has a predicted life span of 100 years which is incredible for a 18 g salamander!