Last night I was trying to do a quiet 'le gasp!' action, in touching my character's finger to her lips, however I think it came off like she was trying to shush everyone. Whoopsie. An action-based one would be a nice accompaniment to the speech version, a la '=gasp :dramatic Oh my! -> You dramatically gasp, "Oh my!"
So! Here's some gasp verb ideas. Please, contribute a bit more color to the suggestion if you have it-
gasp lip: Drawing his finger to his lower lip, Person gasps!
gasp surprise: Person gasps in surprise!
gasp plead: Falling to his knees, Person gasps and pleads!
gasp cry: Crying rivers, Person's sobbing is punctuated by heaving gasps.
gasp breath: Person gasps and wheezes as he catches his breath.
gasp loud: Person gasps loudly.
gasp quiet: Person gasps quietly.
gasp help: Person gasps for help!
gasp fear: Person gasps in fear!
gasp drama: Person gasps dramatically.
gasp air: Person gasps for air!
gasp enthus[iastically]: Clasping his hands, Person gasps enthusiastically!
gasp delight: Person gasps in delight!