The Collaborative International Dictionary of English v.0.48:

Artful \Art"ful\, a. [From Art.]
   1. Performed with, or characterized by, art or skill.
      [Archaic] "Artful strains." "Artful terms." --Milton.
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   2. Artificial; imitative. --Addison.
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   3. Using or exhibiting much art, skill, or contrivance;
      dexterous; skillful.
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            He [was] too artful a writer to set down events in
            exact historical order.               --Dryden.
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   4. Cunning; disposed to cunning indirectness of dealing;
      crafty; as, an artful boy. [The usual sense.]
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            Artful in speech, in action, and in mind. --Pope.
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            The artful revenge of various animals. --Darwin.
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   Syn: Cunning; skillful; adroit; dexterous; crafty; tricky;
        deceitful; designing. See Cunning.
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WordNet (r) 3.0 (2006):

artful
    adj 1: not straightforward or candid; giving a false appearance
           of frankness; "an ambitious, disingenuous, philistine,
           and hypocritical operator, who...exemplified...the most
           disagreeable traits of his time"- David Cannadine; "a
           disingenuous excuse" [syn: disingenuous, artful]
           [ant: artless, ingenuous]
    2: marked by skill in achieving a desired end especially with
       cunning or craft; "the artful dodger"; "an artful choice of
       metaphors" [ant: artless]

Moby Thesaurus II by Grady Ward, 1.0:

96 Moby Thesaurus words for "artful":
   Byzantine, Machiavellian, Machiavellic, acute, adroit,
   ambidextrous, arch, astute, cagey, calculating, canny, chiseling,
   clever, collusive, covinous, crafty, crooked, cunning, cute,
   deceitful, deep, deep-laid, designing, devious, dexterous,
   diplomatic, dishonest, disingenuous, double, double-dealing,
   double-faced, double-minded, double-tongued, doublehearted,
   duplicitous, facile, faithless, false, false-principled,
   falsehearted, feline, finagling, forsworn, foxy, fraudulent,
   furtive, guileful, indirect, ingenious, insidious, insincere,
   inventive, knowing, oily, pawky, perfidious, perjured, politic,
   ready, resourceful, scheming, serpentine, sharp, shifty, shrewd,
   slick, slippery, sly, smooth, snaky, sneaky, sophistical, specious,
   stealthy, strategic, suave, subtile, subtle, superficial, supple,
   surreptitious, tactical, treacherous, trickish, tricksy, tricky,
   two-faced, uncandid, underhand, underhanded, unfrank, unsincere,
   untruthful, vulpine, wary, wily