as a result of the research i have conducted there are 3 methods:[list=1][*]nipple suction
as described on already listed sites and here and here
regular application of suction caps will eventually result in elongation of nipples (but it takes time and patience – lots of it!)
[*]surgical
being most invasive of them all of course gives the best results fastest check here
[*]stretching applied through the jewelry that requires piercing
this was something i was personally looking into, and was recommended to me by my piercer. best way would be to put a barbell into the nipple and than add rings behind it pushing nipple out. one has to be careful not to put undue strain on the piercing and cause its migration, but over the time, as more rings are added nipple will be pulled out – permanently (something like tribal neck ringing)[/list=1]
hope this helps