I am now using a perl bbs script as a novel submission and discussion board for my visitors.
However, the title sorting job has to be done manually and I find it quite time consuming.

Is there any php+mysql board script that allow the users submitting their posts without registration (better to have no registration and signature system) and can be sorted by thread name and author name?

Thank you very much for your help!

yea, use Invision Power Board, its free, and one of the best ones out there. http://www.invisionpower.com/

Invision is good indeed. another very good one is phpBB: http://www.phpbb.com/