Repeated work?

It's a good question. Chiefly, I don't think menu_block was available when I originally wrote this (it's been in use for 13 or 14 months prior to my submitting it here). At the moment, this module has two features that menu_block lacks which, in the kinds of projects I often work on, are indispensable:

1. Unique id on every list item regardless of the number of blocks produced by the module (menu_block's list items contain useful classes, but these are not unique if it should happen that the same menu items appear in more than one block on the page--you might run into such a situation on a page containing both the entire menu tree in a flyout menu and a submenu), and
2. The ability to change all class attribute values on list items and parent menus (so that i.e. menus can be more easily styled differently than Drupal's various default menus)

Clearly both of these issues can be resolved with CSS alone, but the added convenience for my work on Drupal themes was more than sufficient to make writing the module worthwhile :)

With respect to the various other menu blocks, I don't think that any of them offer the base functionality included here. Forthcoming features (mostly having to do with theming) in this module should further differentiate it from the existing offerings.

Done. Thanks for the feedback.