I have a small, hardbound book, 45pp, heavily illustrated (Great Furniture Styles 1660-1830).  The only problem is - no ISBN (because of its age).  Can I post this?  It's certainly not a pamphlet, it's just small.  But under 50 pages.  Maybe I should offer it as a freebie.  It's a nice little book.

Sounds like it's too small to be posted. I found the information here...

http://www.paperbackswap.com/help/search.php?terms=pamphlet#booklet

Pamphlets/Booklets/leaflets without ISBNs: NO

• These sometimes contain advertising; members also complain at having to pay a credit for these.
• Leaflets = non-children's books with less than 20 pages
• Booklets = non-children's books with less than 50 pages
• Leaflet/pamphlets/booklets with ISBNs may be posted
  • if so, the number of pages must be included in the item description.
• Children's books do not count as booklets or leaflets, even if they are short. 
  • Children's books can be expected to have short pagelengths and the booklet/leaflet designations do not apply.

That's what I thought.  The thing that's irritating is that the only reason there isn't an ISBN is because it was printed in the mid-'60s.  The identical book, new, would definitely have an ISBN.  Oh, well.