For anyone interested in using gesso, there’s an informative discussion about brush-on primer at the Steve Dean Forums that is worth checking out. It includes a variety of anecdotes about the trial-and-error process, tips, and recommendations.
Also see the thread “Wow – I’m not sure I will ever go back to spray priming” over at the Privateer Press forum.
DakkaDakka has a mirror of Hyun’s gesso article on their site, too.
On Frothers, see “Priming figures with Gesso.”