My b2evolution Version: Not Entered
How about a plugin/widget/whatever that can be installed on the blog page, letting the reader choose between ascending and descending order? I know this can be toggled from the Blog Settings page, but what about the reader? When the content is something that builds on itself, a new visitor might want to read from the beginning, or skim the conversation in order; someone returning might want to see what's newest.
EXAMPLE of when this would be critical: I have this stalled project I want to get back to--it is close to the use case described on http://manual.b2evolution.net/B2evolution_vision. I imagine different "blogs" as chapters of a book, and multiple invited authors discussing each chapter's issues, with comment additions from others. (My initial mockup used two blogs for each "chapter"--one for the "conversation" or text, and one for links and references: the chapter's "bibliography".)
This kind of use would be one for which a viewer-accessible toggle between ascending and descending display would be appropriate--perhaps even necessary for someone beginning to visit the project in midstream!