The only condition for using Ligature is that you include a link to http://www.desiquintans.com/ligature somewhere on every page. You can use an image as a link as long as the image's ALT text is "Published by Ligature" and the image links to http://www.desiquintans.com/ligature.
Thanks to Alex King, whose Javascript library JS QuickTags I took, stripped down and reused as The Punctuator, which is licensed under the GPL if it comes bundled with Writer's Block. An extended version of The Punctuator under the LGPL can be downloaded from http://www.desiquintans.com/punctuator.
Thanks to Mark James for the Silk icon set, which the Ligature Admin section uses.
The password resetting feature requires PHP to have access to a mail binary like Sendmail. If a user doesn't receive an email after resetting their password, ask your web host if your compilation of PHP can use Sendmail or some other mail binary.
The bug report feature also requires PHP to have access to a mail binary.
The Punctuator uses Javascript to insert HTML entities. The Mass-delete form also uses Javascript to automatically bring the text field into focus. These features require Javascript to be supported and allowed in your browser.
Some of the best user-friendly features of the Admin section's User Interface (like icons that turn into buttons when hovered over and extra-big clicking areas) don't work with Internet Explorer. These features were specifically added to make the UI easier to use, but the standards-ignorance of Internet Explorer (even IE6) makes this impossible. Unless you don't mind clicking on 16x16 pixel squares to get things done, I suggest changing to a standards-compliant browser like Firefox to make your life easier. Seriously, 16x16 is small.