There are, roughly, several hypotheses on the subject of the afterlife:
1. The Materialist stance
2. The Animist, with a few subvariants, spanning from some sort of immortality of one ( or more ) soul(s) among the entire spectrum of an individual, via survival in a tribe/group ( "antlike immortality" ), not as an individualized conscious subject ( because one hadn't been one during his earthly life, just a part of a group ), but as an "atom" or "cell" in group soul of a tribe, to the more familiar dungeon-like shadowy anemic quasi-existence in Hades/Sheol.
3. "Ethical immortality": after death, one either enters in a cataleptic hybernation, or is "judged" ( by his deeds or faith, doesn't matter ) once or many times. This is frequently set in a resurrectionist framework with heavens and hells.
4. Fall into matter and return into the source. This scenario can be staged only once, or many times ( reincarnation ).
5. In the case of reincarnation, it is either illusory ( Buddhism, Advaita ) or real. Also, it can be interpreted as a wheel meaninglessly circling, or as the crucial means of gaining experience, ethical perfection and so on ( various branches of theosophy ).
For a comparative look at different religions and their understanding of the afterlife see
afterlife beliefs - James Lewis' afterlife religious studies
- has a page on every religion
part of the Near-Death Experiences & the Afterlife site