Yeah...the 'contract' in-between lives stuff comes from a lot of different spiritual belief systems, actually.
I first read about it when I read all the Seth books (Seth Speaks, The Nature of Personal Reality etc...) and The Holographic Universe in amazing book for this too! You should definitely read the latter...totally amazing. I think I copied an excerpt from The Holographic Universe on the in-between Life State somewhere around here. I'll find it for you....then you'll have to get the book - it's a super-goody!