There are a lot of misconceptions about Viking burials in popular culture nowadays. However, one of the foremost burial traditions of the Vikings is the ship burial. The deceased Viking was placed in a wooden or stone ship, along with grave offerings which could indeed include live slaves, sacrificed to die with the Viking. The ship would then be covered with stone and soil, creating a burial mound.
Even if it was a cremation—which was common, grave goods would still be given, such as weapons, or even tools for those who were blacksmiths, or jewelry for women.