Storing the actual marked up signature in the database to reduce calls to do_markup on post display.
Added an option to upload post icons from the admin control panel.
Added a database tablename prefix to the config file and the installer so users can specify a custom tablename prefix to use for all tables.
Added a new option when editing a post that allows a user to delete the attachment from the post or upload a new one if attachments are turned on.
I
really like the last 3