I liked Montauk's book as it has a lot of sample essays. not, mind you, to copy stuff off from .. but to get a general idea of the question, and some sample essays of admitted applicants ..
I also have the book 'Marketing yourself to top mba programmes' by Phil and Carol Carpenter from HBS. Though this book is even older than Montauk's (refers to apps on disks!
), this is pretty insightful .. I especially liked the personal evaluation questions section there .. these questions helped me analyze my goals/interests/background, etc
Cannot comment on the 88 tips .. unfortunately I also didnt know about the mbagameplan .. I think that seems to be pretty good too.