Climb Tasmania publishes a number of excellent guidebooks to areas in Northern Tasmania written by Bob McMahon and Gerry Narkowicz.
They are available at most outdoor shops in Tasmania and at http://www.osp.com.au/htm/climbing.html

Covers the Cataract Gorge

Covers crags along the North Esk river, including:

Covers crags along the South Esk river, including:

Covers many varied crags in the north of the state, including:
Ben Lomond is next on the Climb Tasmania agenda. Hopefully out in 2005 sometime.