Ask HN: Thoughts on code samples post-interview

Would it be a waste of time to write a custom code sample, and related to the business somehow? Or should I just send something already completed. If not a complete waste of time, any interesting ideas as to what to create?

TL;DR Looking for ideas for a code sample, but is it worth it?

Requirements: Something simple, but not a scraper, as I feel if someone else decides to create something new for their code sample, they'd more than likely create a scraper of some description.

Background: I applied for a job, and after 4 successful interviews, they've asked for a code sample. They're a web-based company, with a private clients area, of which I don't have full access to, yet. Definitely want this job, and want to stand out from the other interviewees. I have been working as a web developer for over 13 years, but this is the first time I've ever had to supply a code sample that wasn't just the interviewer looking at my portfolio/references, so I'm looking at HN for some feedback.