Have started doing significant SEO work lately (after long period of working exclusively on development) and got a chance to experiment with link building techniques and in particular profile links.  Mind you I do all the experimenting on non customer sites before I decide its worth the trouble and the risk.  I usually use my own domains that don't bring in any significant amount of money or use friend's sites after I explain the risks to them.  In this particular experiment I have used a friend's site.