A respectful suggestion that the tabs up top limit ease of use, since any excessive use or lengthy wording causes them to double, triple, quadruple up the tab bar. It might instead be useful to introduce something akin to:

-----------------------+------------------------------------------------+
Home | Existing to do box; the list names could go |
-----------------------+ to the right of this box, instead, if you so |
Work | desired, but that would of course get in the |
-----------------------+ way of what's already there. |
Really Long Tab Title | |
-----------------------+ |
Flippygippydoody | |
-----------------------+ |
So on you get the idea | |
-----------------------+ |
| |
| |
| |
| |
| |
| |
| |
| |
+------------------------------------------------+

If that doesn't come across well, I'm thinking of something that looks like a Web interface version of this:

http://brok3n.org/soc/tabs-vertical.png

I think it'd be simply more functional than the existing tab bar, given the impositions that tab bar makes upon length of list names and number of lists.