With a little bit of work, you can get short monophonic vocals into Serum's wavetable synthesizer. If you scan through the wavetable at a constant speed while playing a note, it will actually reproduce the the vocal sample. So by applying an envelope, LFO, or manual automation to the wavetable position you can get a lot of different articulations off the same vocal.
I've been tossing up whether to buy Serum or not for a while but this probably made the decision for me - Sounds like a really cool way to make subtle (or not so subtle) changes to vocal samples.