Brian Droitcour's Rhizome article about Jstchillin.org provides some grist for Duncan Alexander's broad generalizations regarding two types of net artists.
Alexander's argument in sketch form:
Camp 1: "The net is their vehicle for dissemination, and they stand out from the online flow"; "design heavy" pages that look like art pages and are a final destination for the surfer (I added the non-quoted part). Examples: Computers Club, Oliver Laric
Camp 2: "This camp makes art for the net on the net, and blends in to the net-social fabric." Examples: Various Dumpers and Tumblrers
To the extent Droitcour describes Jstchillin as having a "top-down organization and meticulous calendar" that sounds like Camp 1. To the extent Droitcour describes Nasty Nets and dump.fm as "touching the issue of chill time by adapting its form" that sounds like Camp 2.