WordNet (r) 3.0 (2006):

come on
    v 1: appear or become visible; make a showing; "She turned up at
         the funeral"; "I hope the list key is going to surface
         again" [syn: come on, come out, turn up, surface,
         show up]
    2: move towards; "We were approaching our destination"; "They
       are drawing near"; "The enemy army came nearer and nearer"
       [syn: approach, near, come on, go up, draw near,
       draw close, come near]
    3: develop in a positive way; "He progressed well in school";
       "My plants are coming along"; "Plans are shaping up" [syn:
       progress, come on, come along, advance, get on,
       get along, shape up] [ant: regress, retrograde,
       retrogress]
    4: start running, functioning, or operating; "the lights went
       on"; "the computer came up" [syn: go on, come up, come
       on] [ant: go off]
    5: occur or become available; "water or electricity came on
       again after the earthquake"

Moby Thesaurus II by Grady Ward, 1.0:

233 Moby Thesaurus words for "come on":
   accost, achieve success, advance, alight upon, allurement,
   ameliorate, amend, anticipate, appear, approach, appropinquate,
   approximate, arise, arrive, await, bait, baited trap, be a success,
   be destined, be fated, be imminent, be in store, be so, be such,
   be to be, be to come, bear down on, bear down upon, bear up,
   blunder upon, break through, brew, bump into, bunco steerer, butt,
   c, chance, chance upon, charm, cheat, chump, clear,
   clear the hurdle, close, close in, close with, come, come across,
   come after, come along, come closer, come forth, come forward,
   come into being, come into existence, come near, come out,
   come through, come up, come up against, come upon, con man,
   confidence man, confront, contrive, cover ground, crop up,
   cut a swath, cut the mustard, decoy, decoy duck, develop,
   discover serendipitously, do well, double-dealer, draw near,
   draw nigh, draw on, drawcard, drawing card, dupe, encounter,
   endearment, engineer, enjoy prosperity, ensue, enticement, expect,
   face, fall guy, fall in with, fare, farewell, flimflammer, follow,
   foresee, foretell, forthcome, gain, gain ground, gain upon, gather,
   gather head, gather way, get ahead, get along, get by, get on,
   get on swimmingly, get on well, get there, go, go after, go ahead,
   go along, go far, go fast, go forward, go on, go places, go well,
   graduate, ground bait, grow better, gull, gypper, hack it,
   hang over, happen upon, have it made, hit upon, hook, hope, hover,
   impend, improve, inherit, inveiglement, lie ahead, lie over,
   light upon, look for, look forward to, look up, loom, lower, lure,
   make a breakthrough, make a success, make good, make good time,
   make head against, make headway, make it, make out, make progress,
   make progress against, make strides, make the grade,
   make the scene, make up leeway, manage, manage somehow, mark,
   materialize, meet up with, meet with, meliorate, menace, mend,
   move, move forward, muddle through, narrow the gap, near,
   negotiate, overhang, pass along, pass on, perk up, pick up, pigeon,
   plan, plot, pop up, predict, present itself, proceed, progress,
   project, prophesy, prosper, proximate, put over, put through, rise,
   rogue, roll, run across, run into, run up against, sap,
   scrape along, seducement, shape up, show improvement, show up,
   sidle up to, skyrocket, snare, spring up, stack up, stem,
   step forward, step up, stumble on, stumble upon, succeed,
   succeed in, sucker, swing, swing the deal, take off, temptation,
   threaten, trap, travel, trickster, tumble on, turn out,
   turn out well, turn up, worry along