It would be nice to see the original plugin updated for 1.5 (since it doesn't say if it is tested for 1.5, just 1.2).
Also, it would be nice if there was an easier install of the plugin.
Also, it would be nice if when the plugin is installed if it would change the formatting buttons above the post form from the html to bbcode AND if that toolbar was shown above the comment post form as well.
I really think bbcode is easier for people to use and it would be nice to have a very step-by-step instructions on how to completely convert WordPress from html markup in posts and comments to bbcode.
I see bits and pieces of the solution I want strewn throughout this forum and the web, but I just don't have time to hack it all together and post up instructions.