Also, other than referring to some Yogamimamsa articles on the subject you don't mention one of nauli's most important functions, that of creating the vacuum in the stomach that enables the yogi to perform basti (the auto-enema, and vajroli-mudra, urethral suction. I can vouch for its efficacy in the former, but have not (and will not!) try the latter.
The reason I left out basti and vajroli-mudra is that I didn't want to turn off people with descriptions of bizarre advanced practices. I figure most people have their hands full just dealing with nauli. However, it'd be great to discuss those practices in these forums if/when there is a critical mass of interested visitors.