WordNet (r) 3.0 (2006):

great deal
    n 1: (often followed by `of') a large number or amount or
         extent; "a batch of letters"; "a deal of trouble"; "a lot
         of money"; "he made a mint on the stock market"; "see the
         rest of the winners in our huge passel of photos"; "it must
         have cost plenty"; "a slew of journalists"; "a wad of
         money" [syn: batch, deal, flock, good deal, great
         deal, hatful, heap, lot, mass, mess, mickle,
         mint, mountain, muckle, passel, peck, pile,
         plenty, pot, quite a little, raft, sight, slew,
         spate, stack, tidy sum, wad]

Moby Thesaurus II by Grady Ward, 1.0:

60 Moby Thesaurus words for "great deal":
   a deal, a great deal, a lot, abundantly, as all creation,
   as all get-out, batch, beaucoup, considerable, considerably, deal,
   ever so, ever so much, galore, gobs, good deal, greatly, heap,
   heaps, highly, in great measure, largely, lashings, loads, lot,
   lots, mess, mint, much, muchly, never so, no end, no end of,
   not a little, oodles, pack, peck, pile, piles, plenty, pot,
   pretty much, quite a little, raft, rafts, scads, sight, slew,
   slews, so, so very much, spate, stack, stacks, tidy sum,
   to the skies, very much, wad, wads, whole slew