Along with BruceTognazzini and AlanCooper (and others), one of the RespectedSoftwareExperts in the field of UsabilityEngineering.
Jakob's website, featuring a bi-weekly column about web usability, is at http://www.useit.com/.
JakobNielsen, a usability researcher at Sunsoft and author of the book UsabilityEngineering, finds that the web is rarely read, but often scanned. The examples he gives in this short results summary show how to write to be well scanned.