It’s becoming quite common for employers to ask to see code samples from prospective developers. This doesn’t really go far enough.
The next step up is to see the VCS history as well. A small sample – say, a couple of hours of work – can reveal a lot about how a person works – more than the code itself. Do they write tests first, or do they backfill later? Do they refactor their code to promote readability? Do they commit regularly, with meaningful comments, or do they just push bits in randomly?
So the next time an employer asks for a code sample, take it up a notch and give them the entire history as well. (And yes, I practice what I preach)