Online To Do list versus Offline To Do List

I already commented on using project issue tracking as a to do list, and I like it. As with all of these things there are plus points, and there are negative points.

On the plus side, I can access my to do list anywhere I can get online. I can take out my iPod touch and with a wifi connection see what I've got to do, I can even add new items and update items already there. I'm hoping this is also true of my blackberry, but I actually don't know, I've never tried from there.

I like that I can categorise my tasks, I can add comments, basically I can put a lot of annotation on each task, and that comes in pretty handy. The system also automatically keeps track of a few stats, and has a built in advanced search functionality.

What I don't like, is that I can't save a local copy, that I can edit and then sync back online next time I get internet. This has, so far, not proven itself to be a major problem. I use Check Off on my MacBook to make really quick notes, and then sync them up manually later. Not ideal, but it gets the job done.

I have access to Trac as part of my research, and I use many of the features for my research, but not to track my to do items. I tried it, but it just wasn't what I was looking for, despite the tight integration with a number of local applications.

Ideally, I would like the system I have right now online (I particularly like that it's my server and my domain that hosts it, I don't want to give Google all my data), with a little local application that did a two-way sync allowing for offline access, and a tertiary concern: if there was an iPod Touch/iPhone application that synced with the list too, it would be handy! Not too tall an order... I'll keep looking.