Online courses are not all that different from what a large portion of scuba instructors are doing already.
Many courses are set up these days for self study. You get the Open Water kit (PADI has one, and apparently from what was mentioned earlier by another poster, NAUI does the same), read it on your own, fill out the knowledge reviews and get with an instructor for the quizzes, pool work and open water dives. The days of going to class a couple times a week for several weeks and then having an open water weekend are getting less common. The quizzes and pool work should take a half day to full day or couple half days to complete prior to your open water dives - Just about everyone in Hawaii is set up to train that way, I've heard it's becomming quite common elsewhere too.
I'm not completely up on the online program, but it's probably similar, but on line rather than having a book physically in front of you. Make sure this course is sponsored by a legitimate recognized agency and that you do indeed have an instructor that can finish you off - I know of one self-styled online course out of Arizona which makes claims that everyone will accept it, used to make claims that everyone would give you discounts because of it, etc, that has had legal teams from at least PADI, and I suspect others, who've said this is not the case. If the course you are looking at is the SDI course, you should be able to find someone to finish you off, but make sure first before getting started.
It seems if your friend is only able to do the course where they live, then their bet bet is to hook up with the local instruction and try to make a schedule work. If your friend decides to fininsh their course elsewhere, then there are options to do it on their own schedule, not just online.
Good luck,
mle_osu:
Seems like it would be nice and convienent for the class room work, but are these real? Can one trust getting their certification thru an online class? granted, the pool work and open water dives are not online and are done thru the LDS... but I cant seem to find the actual Agency that certifies the divers... just says "accepted everywhere" and "Our certification is RSTC certified and credited."