Issue Tracking / To Do List / Ticket System for Drupal 6.x

Hello!

I'm running Drupal 6.4 (yes, I know, I know, 6.5 is out, I'm working on it! ;) ) and for the life of me I can't find a working Issue Tracker / Ticket system.

I'm using it for internal development and projects, very few of which are software related. For the most part, I am really looking for a to-do list with the ability to task users and track project progress.

So far as I can tell the Project module, and the Issue Tracking module for the Project module are not 6.x material.

I have played with Storm, but:

1. That's a bit of overkill for me.
2. For all the features it has you don't seem to be able to assign issues to a user for resolution.

What I am looking for functionally:

- Issue description and nesting -- project / issue. Sub-issues (if possible).
-- e.g. "Project: Complete Finance Documentation" "Issue: Determine Interest Rates" "Issue: Calculate Rate Return Model"
- Completion tracking at the issue level at least if not the project level.
- Ticket generation describing a task with some kind of reminder/email pestering (optional, but desired).

Anyone? Help?

Thanks in advance for your responses.

-ali