Just like everyone else, I've applied and interviewed for a development job or ten. You know the situation… you kick off your resume, get a time for an interview, walk in with another copy of your resume, and talk about your past projects. If the interviewer subscribes to the Microsoft Model of interviewing, they may give you one of the silly “How many gas stations are in Los Angeles?” questions.
But what is really the point of this question? Obviously they don't – well maybe the more sadistic ones do – expect you to solve it. The standard line of reasoning is that this “demonstrates how you think”. With the exception of developers who work for Exxon-Mobil or in GIS, this is just a plain silly question which has zero relevance and is not even anywhere close to the types of most of the problems you solve, let alone the area.
I've decided to take a completely different route. After a friend of mine put together a simple portfolio, I have decided to do the same.
I want to do a service for myself and the interviewer by giving them something they can see, hold, examine, and even given a copy of if needed. Obviously I'm not going to risk threatening any confidentiality agreements, but I'm going to include screenshots of applications that I've built, a simplified/genericized database model that I have built, and misc pieces of functionality. And to top it off, I'll be prepared to discuss all of it in detail.
This is an interviewee's chance to shine on their own ground and discuss/demonstrate some skill. Do it.