Come on, let's have a bit of fun, all this PR-building gets a bit much! What's the silliest, or most pointless bit of link-building you have done? Currently, a stupidly large proportion of referrals are coming from some gardening site where I happened to ask a genuine question about some houseplant I was having trouble with (no, really!) and included my URL in my sig, and now every other visitor is from there! Not exactly targetted... Wish all link-sowing was that successful though...
A while ago I worked for a SEM company and discovered that the links that I submitted to a certain directory were getting recognized very quickly and so put it at the top of my list for link building. I never realized that it was also a dating site. One day a sales guy at my firm asked me for a good directory link to give a buddy and I gave him my favorite. He came back huffing and puffing later in the day informing me that I had embarrassed him by giving him a link to a dating site. Well, it's a good, respectable website even if it does have a dating component and the directory is top notch in my opinion. It also now has a PR of 5 and my links are still working for me
You can check your stats and see the visitors stop time on your website and how many unique visitors were turned to returning visitors. Or the traffic from there will be useless.