There are also a couple of variant base class monks that would let you multiclass into classes that have abilities, spells or powers that would let you defeat or bypass DR in some way.
http://www.enworld.org/forum/general-rpg-discussion/221182-monk-database-now-added-detail.html?pp=15
Monk (OA p18). Note: adds new Monk weapons & free multiclassing
Monk (FR p25, Champions of Valor p36) Broken Ones- multiclassing w/Clerics, Divine Champions, Arcane Devotees, Divine Disciples, Hierophants, and Divine Seekers of Ilmater
Monk (FR p25) Dark Moon- multiclassing w/Sorc, Monk & Sorc must be within 2 lvls of each other
Monk (FR p25, FR:Shining South p32) Hin Fist- multiclassing w/Ftr, Rog, Pal. Note: in FR, it is implied that this is a base class, while in FR:SS it is described as a variant of the Sacred Fist PrCl (see PrCls below).
Monk (FR p25, PGtF p65) Long Death- multiclassing w/Ftr, Assn, Blackguard
Monk (FR p25) Old Order- multiclassing w/Roc, Sorc, Shadowdancer (Monk lvls> all other lvls)
Monk (FR p25) Shining Hand- multiclassing w/Wiz ( Monk Lvls ? Wiz lvls)
Monk (FR p25, Champions of Valor p34 CoS: Waterdeep p41) Sun Soul - multiclassing w/one other class as long as Monk lvls highest
Monk (FR p25) Yellow Rose- multiclassing w/Rgr & Shadowdancers
Monk (UA p52) Fighting Styles: Cobra Strike, Denying Stance, Hand and Foot, Invisible Eye, Overwhelming Attack, Passive Way, Sleeping Tiger, Undying Way
Monk (Eb p38) multiclassing & feat options