Short of opening two accounts, perhaps you could use wcall and pcall to distinguish between work and personal matters? Or callw and callp, &c.?

I gave up trying to keep these things separate in my head, but more power to you if you can.

Sure, I can play around with tags, but then this makes the overview roll-up of tasks useless, as the two would be totally blended.

Well, one approach is to have a pers and a work tag, and then have roll up lists for your pers stuff and your work stuff, e.g., tag:pers AND tag: call versus tag:work AND tag:call.

All I am saying is that smartlists are very smart aggregators, and a real recurring theme on these boards is that inventive uses of smartlists and tags can often emulate the features people wish the RTM crew would build in. Is this as good as if it were built in? Maybe not. On the other hand, for a service that is free to most (nearly all?) of its users, I think that smartlists let people optimize their system to work as they wish, while freeing Bob to do all those things Bob does. If features were a popularity contest, he'd be working on start dates or sticky due dates or somesuch, but only the people who feed him bananas know what's really next.