Combination of things I can't multi-task

In a recent comment on Ken Allen's blog, Karyn Romeis cited some studies that indicated that it is not whether we can multi-task or not, but rather what actions we can multi-task in combination. This got me to thinking about what I can and cannot multi-task.

What I can't multi-task:

I can't drive and talk at the same time
I can't write my blog and listen to what my kids are saying
I can't cook and plan the next day's schedule
I can't correct papers and plan tomorrow's class
I can't search for something on the internet and listen to my kids


Things I can multi-task

I can drive and listen to my kids' stories
I can read blogs and listen to what my kids are saying
I can cook and read
I can correct papers and watch TV
I can search for something on the internet and give my kids directions

Things I can never multitask

Finally, there are somethings that I need total concentration for, with no ability to multi-task as I work on these things:

Driving during poor weather
Writing a paper (including my dissertation)
Analyzing data
Transcribing
Taking down numbers or writing something that is being spelt out for me.

What does this mean?

In analyzing those that I can and those that I can't multitask in combination, I think I have trouble multi-tasking when there are two communication inputs or two communication outputs (creating and listening, for example). I also cannot multitask when the task itself is complex (a multitask) and I am still developing heuristics to accomplish the task. Once I have the skills or heuristics, it is easier for me to multitask as I can go on "auto-pilot" for those tasks for which I have developed heuristics.

I am not sure if this is something universal or unique to me (i.e. Gardner's "intelligences" where some might be able to multi-task using those skills in which they have an innate ability). I'd be interested in know what other people can and can't multi-task.