Dynamic Session Timeouts – Rewarding site progress with a longer session

People still use in-language session mechanisms that run out of memory?

Let me clue you into something.

Professionals don't.

If you're selling something, you don't EVER want to dump a shopping cart on the floor. It seems natural to you, from your self-centered perspective, that it's OK for a session to time out after a week, but from a user's perspective they can leave Microsoft Word running for a week and it still works.