The Collaborative International Dictionary of English v.0.48:

Awfully \Aw"ful*ly\, adv.
   1. In an awful manner; in a manner to fill with terror or
      awe; fearfully; reverently.
      [1913 Webster]

   2. Very; excessively. [Slang]
      [1913 Webster]

WordNet (r) 3.0 (2006):

awfully
    adv 1: used as intensifiers; "terribly interesting"; "I'm awful
           sorry" [syn: terribly, awfully, awful,
           frightfully]
    2: of a dreadful kind; "there was a dreadfully bloody accident
       on the road this morning" [syn: dreadfully, awfully,
       horribly]
    3: in a terrible manner; "she sings terribly" [syn: terribly,
       atrociously, awfully, abominably, abysmally,
       rottenly]

Moby Thesaurus II by Grady Ward, 1.0:

139 Moby Thesaurus words for "awfully":
   abominably, agonizingly, alarmingly, almighty, appallingly,
   astoundingly, atrociously, awe-inspiringly, awesomely, awful,
   awingly, badly, baldly, balefully, basely, bestially, big,
   bitterly, bizarrely, blatantly, brashly, brutally, confoundedly,
   contemptibly, cruelly, damnably, damned, deadly, deathly,
   despicably, detestably, deucedly, disconcertingly, disgustingly,
   dismayingly, distressingly, dolorously, dreadful, dreadfully,
   eerily, egregiously, exceedingly, excessively, excruciatingly,
   exorbitantly, extraordinarily, extravagantly, extremely, fearfully,
   flagrantly, forbiddingly, foully, frightfully, fulsomely, ghastly,
   greatly, grievously, grossly, gruesomely, hellishly, hideously,
   horrendously, horribly, horridly, horrifically, horrifyingly,
   hugely, improperly, incomparably, inexcusably, infamously,
   infernally, inordinately, intolerably, just, lamentably,
   loathsomely, mightily, mighty, miserably, much, mysteriously,
   nakedly, nastily, nauseatingly, notoriously, numinously,
   obnoxiously, odiously, offensively, only too, openly, outrageously,
   painfully, piteously, powerful, powerfully, pretty, quite, real,
   really, remarkably, repugnantly, repulsively, revoltingly, right,
   sadly, savagely, scandalously, shabbily, shamefully, shatteringly,
   shockingly, so, something awful, something fierce, sordidly,
   sorely, staggeringly, startlingly, terribly, terrifically,
   torturously, tremendously, unashamedly, unbearably, uncannily,
   unconscionably, unduly, unpardonably, very, very much, viciously,
   vilely, weirdly, whacking, whopping, woefully, wretchedly