I'd be VERY careful. I got my PhD from one of the biggest and best national universities in Australia and had a hard time getting it accepted in the US when I returned home, and online degrees are viewed with even cynically.
There are a few 'brick'n'mortar' universities that do offer online PhDs. I suggest you look at them first (University of Michigan comes to mind first). Places like A Capella, Phoenix, etc... do not have a good reputation for PhDs. In fact, one of Capella's PhD candidates posted their thesis survey on a discussion board I am on and it was TERRIBLE. The questions were vague, didn't address what they were looking at, etc.... I had to point out that their survey was fatally flawed and ask if their supervisor had approved it. I then went on to point out that at most universities I know of, if a student sent a survey out that was that ill-formed, they would risk being dropped from the program for incompetence. Funnily enough, the student pulled the survey from the board -- but not before I contacted their supervisor (who had NOT seen the survey). *sigh*
And THAT is why I say be VERY cautious with online PhD programs. Most are diploma mills, and the quality of the degree is VERY shoddy. Why spend so much money to do a degree at a school that may not get you a job.
That said, I would also strongly urge you to check out ANY university you are thinking of applying to, with the HR department of the college you want to work for. Make sure they would accept the degree before you outlay ANY money on it.
Good luck!