I think you might attract more business if you were to provide a link to a website with some samples simply because who wants to go through the hassle of ICQing some guy that they may not be interested in doing business with in the first place? However if they were to click a link and see that you do high quality work, of course it would be worth going through the trouble to contact you.
But requests for work on these boards are a dozen. Those who provide high quality samles up front, tend to be the ones who get the paid jobs.
