I am going to second the psbook recommendations but add this as a separate answer to note some of the complexities and what would be lost in what you are doing. Chances are this is not a problem (I assume you are trying to print the book, not click on pages with a mouse) but basically this limits you to the PDF features available in Postscript (no hyperlinks etc) and to note one possible alternative (depending on what exactly you are trying to do).
In general, the printing of signaitures is somewhat complicated. You don't have 1, 99, 2, 98, 3, 97 etc. Instead you have 1, 2, 99, 98, 3, 4, 97, 96 (or 1, 99, 2, 3, 98, 97 if starting on the other page) if you are only printing double sheets two sided. Additionally you have the issue that this assumes you aren't folding and cutting signatures (only folding them). It looks like psbook only handles the fold and bind method, not the fold, cut, and bind method (with fold/cut/bind, chances are you'd print on A0 paper, 32 sheets to a signature, then cut and fold, so one sheet would become one signature).
There aren't any tools specifically for this that I know of directly in pdf format.
One thing to keep in mind is that if you are generating PDF's yourself from LaTeX, the following is likely to be more flexible and helpful: booklet.sty
That gives you a much richer set of options for printing signatures.