This would include the ability to categorize both posts topics and categories within other Categories.

Add a password recovery feature for administrators who forget their passwords.
Mango does not store the actual passwords, so link sent to admin email will require him/her to reset it.

It would be good if you can add a feature to add multiple blogs in one single instalation. Something simillar to wordpress Mu.

This would be usefull if you would like to offer blog to members of you site.

Add next and previous information to posts. It would only go to next and previous in time, and not be grouped by any of the archive types (ie: it won't matter if the user is coming from a search, or a date archive listing)

Improving the documentation would be great. To be quite honest as a new developer trying to add on to Mange blog is pretty hard because of the lack of documentation.

There needs to be documentation outlining all the data that is stored, the order of operations of each page. What each page associates to, A better example of how to write an addon, better example of how to write a theme, ect.

Create a plugin that will track post views.
Count can be stored in a custom field of the post itself.
Count can be shown using the "beforePostContentEnd" event. The plugin should also provide a custom event to show the count, in case the designer wants to place the number in a different place. The plugin should have a preference setting that will determine whether to use the beforePostContentEnd event or the custom event.

This plugin should seamlessly allow the blogger to add varying sized banners, adwords scripts (or something similar) to the typical areas found on a blog. Near the header, near the footer, the right/left nav and an inline ad within a particular blog post.

I would like to see the ability to have members only content within a single installation of mango blog. This means page and posts could be set for members only viewing. Users would have to log in to view the post or page.

It would be nice if this feature could allow templates to decide how content is rendered for members only content. For example, Display nothing, title only, title and teaser.
An off the top idea might be <mango:Posts count="5" members="titleOnly">

Ultimately, just having a members section would be a great help.

For the average user, figuring out how to use a thumbnail for a larger image is difficult to do. The ability to automatically resize images (possibly using GD or ImageMagick) would make it much more intuitive for users.

It would be nice if we could create a standalone page one that is editable in the admin, but not included in the navigation. Selecting None as the parent makes it a top level page. But I would like to see an option to make it not show up at all unless linked directly to.

Plugin automatic update notification from admin area. I am not sure such functionality exist or not but I love it.
May be plugin will have update url which return current version and admin periodically check version for plugin.

Add support for enclosures. This will include a place to add the enclosures in the admin post form and a set of tags to show it in the themes.

Add the ability to embed swf files into a blog post.

A pod plugin that would show a calendar in the sidebar. It would show dates with entries as links.

An update to the subscriptions plugin or a new plugin that allows a user to subscribe to a post/page's comments without making an actual comment. The plugin could use the same form but ignore the fact that the comment content is empty.

Pages should be shown as a tree in admin

-easily assign post to a different author (great for multiple authors but PR firm edits)
-show only certain authors on blog

It would be nice to have a place in the admin to review/edit/delete the comments and also have a place that I could add a comment "from the admin" that has a special "admin class", so I can style it different from the normal comments.

Implement automatic notification by email to plugin developers when an untrapped error occurs with their plugin (i.e. one that's logged in Mango's error logs). Blog owners should have the ability to opt out of this reporting.

I'd love to see the ability for Mango to use the IntenseDebate commenting system. This seems to be taking WP blogs by storm recently and looks really cool....