The Collaborative International Dictionary of English v.0.48:

Rile \Rile\ (r[imac]l), v. t. [imp. & p. p. Riled (r[imac]ld);
   p. pr. & vb. n. Riling.] [See Roil.]
   1. To render turbid or muddy; to stir up; to roil.
      [1913 Webster]

   2. To stir up in feelings; to make angry; to vex.
      [1913 Webster]

   Note: In both senses provincial in England and colloquial in
         the United States.
         [1913 Webster]

WordNet (r) 3.0 (2006):

riled
    adj 1: aroused to impatience or anger; "made an irritated
           gesture"; "feeling nettled from the constant teasing";
           "peeved about being left out"; "felt really pissed at her
           snootiness"; "riled no end by his lies"; "roiled by the
           delay" [syn: annoyed, irritated, miffed, nettled,
           peeved, pissed, pissed off, riled, roiled,
           steamed, stung]

Moby Thesaurus II by Grady Ward, 1.0:

42 Moby Thesaurus words for "riled":
   aggravated, angered, angry, annoyed, bothered, browned-off, bugged,
   burnt-up, chafed, cross, disturbed, exasperated, galled, griped,
   incensed, indignant, irate, ireful, irked, irritated, livid, mad,
   miffed, nettled, peeved, piqued, pissed, pissed-off, provoked,
   resentful, riled up, roiled, ruffled, sore, ticked off, troubled,
   vexed, worked up, wrathful, wrathy, wroth, wrought-up