Xhtml Friends Network (XFN) is yet another area of the blogging world. XFN is a technology that can be used to build human relationships networks. Basically, it is an addition to XHTML standard, which allows to mark URLs with a number of relationships, such as acquaintance level, wheather you’ve met a person or not, if he is a part of your family and wheather you are working with him or not.
The URL marking is really easy, but I wouldn’t have bothered with it, unless WordPress supported it. In fact, I’ve learned about this technology from the WordPress. It supports the XFN by default and provides an excellent management interface in the links administration section.
I have therefor marked all my links in the sidebar with appropriate XFN tags and I have also submitted my site for spidering.