Custom module with its own menu block I am trying to create a module that supplies a custom menu block, that changes based on what organic group you are looking at. I'm confused by the documentation, so I thought I'd ask here. I saw an answer for Drupal 7, but I'm using Drupal 6.

og_menu doesn't work for me because I don't want group admins to change it. I just want the default to be dynamic based on some logic of my own.  

Specifically, should I supply a custom block from my module? If so, how do I render the list of links I create, or should be supplying a custom menu? What hook do I use?
Sounds like you'd really want to supply a hook_block, whose $content will call a custom PHP function that will construct your array of links to other organic groups, based on your criteria.