...
Also - is this really a startup or just kind of a cool project? With all the other list things out there, how are you going to emerge enough to make money at it?
Most other list apps are one-dimensional. You have a shopping list and a to-do list. This is a tree that lets you make lists of lists of lists. You can put your entire life into your Simplist and it won't be overwhelming or difficult to manage. My Simplist is seven layers deep in some places, which I didn't even realize until I counted.
Along those same lines, I'm not sure how this qualifies as a start-up as such. It's nifty side project, but it would do you better to present the thing you've created in an honest way.
(www.protopage.com has great to-do list functionality)
I use it for everything--to-dos, favorites, projects, priorities, packing lists, shopping lists...