I spoke to one of my hire's father, one time, because he worked for him for 2 years. You'd be surprised, family members are often the most honest. The point is to get to know the candidate as quickly as possible and make a good decision. Speak with as many people that know them as possible.
(1) Most interviewers won't ask for a 10 hour sample project.
(2) Most interviewers won't ask for 10 references.
(3) Good serverside web dev talent, even in this economy, is not in surplus.
(4) There are extremely talented developers who are just going to say "no" to these weird requests.
Your loss.
I don't mean "unprofessional" as in, "you'll get kicked out of the guild". I mean, "this will make you look bad". It's as much an interviewer's job to sell their company as it is to qualify a candidate. Perhaps if you're getting a stream of people that's so bad you feel like you need to talk to their Mom and get them to work on spec for you, your real problem is that you just have a really crappy hiring pipeline.
But from personal experience, I very much agree that it is also the interviewers responsibility to sell their company. I've been in the fortunate position for some years now that I haven't needed a job. When I move, it's from the position of already being employed. Near the end of a job interview there will usually be the point where the interviewers will ask if I have any questions for them. My stock questions always include:
a) What do you like about working here?
b) What do you not like about working here?
I love observing their reaction/response to question b) particularly. :) And I feel asking these kinds of questions sends a clear message to the interviewers that I am not desperate for the job, which puts me in a better bargaining position when it comes time to talk salary etc. Of course, this tactic only works when you really aren't desperate.