A widget to display a dropdown of public blogs. Goes to target blog on select.
Details: https://github.com/eminozlem/b2-blog-selector-plugin

Demo: http://eodepo.com/b2evo/demo/blog4.php

Dont forget to rename the plugin's folder to blog_selector_plugin or it wont show under Plugins > install new.

You can use below code to use it in your skin if you dont wanna insert the widget 1 by 1 in all of your blogs:
$Plugins->call_by_code( 'blog_selector', array( // Params follow:
'order_by' => 'name',
'title' => 'Pick a blog',
) );