One of the most popular formats for online advertisements, especially amongst blogs, is the 125px by 125px square ad. Who knows why. Perhaps the size makes it easy to use in both narrow sidebars in a single column and wider sidebars as well in two columns. Whatever the reason, it’s popularity is nice for both designers as well as advertisers. Designers because we can design around this block size when creating new designs. Advertisers because having a unified size means having to create less “custom” sizes for each new place they advertise [...]