PUBLIC MARKS from Spone with tag logos

rel="logo" is a proposed standard for serving and maintaining up-to-date logos for use in various media. By including a line of code on your site that links to a scalable vector logo, you make it very easy for other websites, applications, readers, clients, and stations to ensure that they are using an approved logo directly from you.

This roundup was gathered through a combination of top notch Google-ing and What the Font?-ing.