"The Secret World" has a few puzzles or quest stages that can only be done while dead. In one or two cases, it's fairly obvious, other times it might click because of something you see/remember much earlier in a quest chain, or having seen in passing. In these cases, the player needs to suicide in order to, for example, speak to a ghost, find an object that only exists in the ghost-world, find a clue left behind by a spirit, etc.
I think it's used to very good effect and quite creatively in those cases. Good effect because it usually makes sense in context, adds to the feeling/story/theme currently being explored and creatively, because I like the blending/crossover of life/death and the head-scratching moments when it hasn't yet clicked.