benjala: I think that's a bit spread all over the Knowledge Base section - helps to search for words like "deprivation", "Ice play" etc by the search tools - but I know there was some Dom who promised he would record his sub's cries as she was being spanked and then upload them as an mp3 file to rapidshare (his sub had freely accepted to share it).
Other suggestions:
sensory deprivation: a tight hood, ring gag, ear plugs. sub left hooded and tied up for an hour and then made to suck Master's cock through the gag.
the sub, naked or almost naked, cuffs her hands behind her back, kneels and has to eat a turkey sandwich placed in front of her without help of her hands (this would work fine on remote too - thanks hellish!)
nipples pinched and twisted
sub ordered to whip her mound and imagine she is being fucked, and then to write a story or prose piece detailing her fantasy and her thoughts.
(though I'm writing "her", all of these except the last, will work just as fine for male slaves)