Sburb

Sburb is apparently the name of a hot new computer game that John Egbert appears to be interested in, as evidenced by the Sburb poster, Sburb calendar and issue of Gamebro (featuring Sburb on the cover) in his room. According to John's official Sburb calendar, it went into beta on April 7th (for reference, Homestuck began on April 10th, 2009).

The Sburb Logo
Sburb's distinctive logo is a neon-green silhouette of a simple house, broken into seven pieces that do not touch (except for the two halves of its roof). Animated representations of the logo (see below) have the house disassemble and reassemble, with the smallest part spinning back and forth in between.

Sightings Withing the Interface
The Sburb logo has made a couple of appearances in Homestuck's interface. An animated version of the logo (see above) appears while pages are loading. Another version of the logo, also animated but lacking its roof, signifies clickable hotspots.