The Collaborative International Dictionary of English v.0.48:

Bucket shop \Buck"et shop`\
   An office or a place where facilities are given for betting
   small sums on current prices of stocks, petroleum, etc.
   [Slang, U.S.]
   [1913 Webster] bucketful

WordNet (r) 3.0 (2006):

bucket shop
    n 1: an unethical or overly aggressive brokerage firm
    2: (formerly) a cheap saloon selling liquor by the bucket

Moby Thesaurus II by Grady Ward, 1.0:

19 Moby Thesaurus words for "bucket shop":
   barroom, boiler room, boozer, brokerage, brokerage house,
   brokerage office, bunco game, con game, confidence game, drinkery,
   fall to, goldbrick, jump in, set to, shell game, skin game,
   stockbrokerage, thimblerig, thimblerigging