At least in Germany, interviews for academic positions are more like dating than like normal job interviews. If you are good, the department will worry about being rejected as much as you do. If they offer you the position and then you don't accept, they are losing time - they may not be able to fill the position in time -, and it's also bad for their reputation. Each time someone gets an offer from universities A and B and chooses to accept the offer from A, this contributes to the reputation of A and harms the reputation of B.

Whether it's good for you if the committee at one university know where else you have applied and how you are doing there, depends very much on the relative reputations of these universities and how they are judging you. You want them to think that you are the perfect fit, not that you are overqualified and therefore likely to reject their offer (doing well with an application at a much better university) or underqualified and going to harm their reputation that way (as could happen if they make you an offer and at the same time you are rejected by a university with much lower reputation).

Should I tell other interviewers where else I've interviewed?
I am working on a web app that helps people manage their finances.

the app requires users to manually enter key financial transactions on a weekly basis, and there is a strong requirement to make the process as short and friendly to users.

which would be a better approach to this problem - 


display a data grid, where the user enters the data and uses the
keyboard to switch from one data field to the next
display a modal window with a form to take in user data
another solution?

