I'm a bit of a fan of ambiguous endings - but I know that other people want to chew up the final book chapter and spit it somewhere.
What camp do you fall in (and if you've got some books with beautifully ambiguous endings that you liked do tell).
THE LYING TONGUE that I just finished had one of those not all threads are tied up nicely endings and I really liked the way it was done (obviously YMMV).