CAD may have rendered blueprints obsolete, but the sketch journal has had no digital match—until now. Paper, by software developer FiftyThree, responds to a finger or stylus and emulates the variations in line weight, texture, and bleed of conventional tools. Drawings can be stored in virtual journals with customizable covers; then you can email, Tweet, post on Facebook, or stream them to Tumblr. Only the Draw tool comes free with the iPad app; pick up Sketch, Write, Outline, and Color at $1.99 a pop. •