I have a number of books that have been posted for trade for literally years.  Some are obscure titles and other are books that were very popular in their day but their day is over.  I would like to cull out those books that will never be requested but don't want to do so if it has finally reached the top of the queue.  Is there a way to see how many books are ahead of you in the availablity line?

The only time you can know for sure where you are in line (at the end) is when you first post the book.  You can see how many copies of a book are posted by adding the book to your Reminder List, then going to your RL to check, but it won't tell you where you are in line.  The programmers have had on their list for some time a way to figure out how long you can expect to wait before a book is requested, based on where you are in line and how often the book tends to be ordered, but it hasn't happened yet.

You can add the books to your reminder list to see how many are posted, but there is no way to see where yours is in the line.

Not sure if this will help but when I post books I first put then on my reminder list to see how many copies are already available. If I decide to post it I attach a note detailing how many copies in the system and the date I posted it. Sometimes this gives me an idea of how quickly the title is moving.

Good idea, Nancy.  To add a note to the book (that only you can see), click on the title, then on "more options" --> "+ personal note."