Just read a really good story by Van Aaron Hughes, about a generational starship headed to Mars where the crew, instead of suspended animation, is put into a state where time is slowed to 1/20th its normal speed.
The physics of it aren't explained -- in the commentary Hughes says Ed Bryant told him it worked better if he left it unexplained -- but a lot of the implications of the differences in subjective time between the crew and the base station are described. Fascinating.