WordNet (r) 3.0 (2006):

dream up
    v 1: devise or invent; "He thought up a plan to get rich
         quickly"; "no-one had ever thought of such a clever piece
         of software" [syn: think up, think of, dream up,
         hatch, concoct]

Moby Thesaurus II by Grady Ward, 1.0:

52 Moby Thesaurus words for "dream up":
   beget, breed, bring forth, bring into being, call into being, coin,
   conceit, conceive, conceptualize, concoct, contrive, cook up,
   create, dense, design, develop, devise, discover, engender, evolve,
   experience imaginatively, fabricate, fancy, fantasize,
   fictionalize, formulate, frame, generate, give being to,
   give rise to, hatch, hatch up, ideate, imagine, improvise, invent,
   make do with, make up, mature, mint, mold, originate, plan,
   procreate, produce, shape, spawn, strike out, suppose, think out,
   think up, vamp up