Amargasaurus was named for an arroyo (and town) near where it was discovered named "La Amarga". The name means "bitter" in Spanish, and the namesake has characterized the debate as to whether the elongated neck spines supported two closely-placed sails (which would have to meet at cervical 2), or whether the upper parts were covered with a keratinous sheath (i.e. a horn-like covering).
The data is fairly equivocal, but it's worth noting that any sails would either have to have lots of skin folds, or else the neck would basically be stuck in one position, as the long spines would basically lock it in place if they were bound to each other tightly with skin.
Other than the neck spines Amargasaurus is a pretty non-descript dircraeosaurid, although the fourth trochanter on the femur is lower than I've seen on any other sauropod.
Update: Just soft-tissue updates, although this also brings a scale bar and a rigorous version, so you can see how speculative that tail really is.