I've managed to get my hands on a full online copy of the basic U.S. Army Combatives. It seems to me that there has to be a more advanced version of this manual, or an equivalent, in existence. Can somebody point me out to a sort of combatives manual for special operations? U.S. Army Special Forces, for example? If possible, an online copy would be great.

US Army Combatives is US Army Combatives. There is no Special Ops or SF Combatives. The H2H Manual is the official curriculum of the Army.

Units have funds available to bring in contracted civilian instructors to augment training as deemed appropriate by commanding officers. That does not take the place of the official program.

Which manual do you have? There are a couple versions online. FM 21-150 has basic strikes and a few takedowns.
FM 3-25.150 includes groundfighting techniques.

But as Leo stated, there is no special, advanced HTH. The Army likes to shoot things and shell things. HTH is minimally trained. All that "Navy Seals secret martial art" or "spec ops secrets" is crap.

If you are interested in military combatives, download "Get Tough" by Fairbairn and "Kill or be Killed" by Applegate.

US special forces secret:
$20,000 dollars worth of equipment per man along with multi-million dollar backup.

The only "special" training that I remember (1973-1977) was some knife training. I attended both the Jungle survival school in Quarry Heights Panama and the Arctic School at Ft Wainwright Alaska. They were more about staying alive as I remember.. I probably know more about H2H and Survival now, than I did then.

The Marine Corps has a whole martial arts program (USMCMAP) but to date, I haven't been able to get my hands on the manual they use to teach it.

As I understand it, if you want more advanced MA in the military, you need to be eligible for WCAP. Most of the H2H/CQC stuff is very basic stuff designed to keep you from being completely hopeless if you have a weapon problem.

US Army Special Forces "Green Berets" do have a variation of the Printed Combatives Materials.
The training is and has been a form of combat Judo,some refer to it as similar to the WWII combatives program of Fairbairn,applegate and Sykes.
There is also a Special Operations collectors book out in Book stores like Barnes and noble(coffe table editions I think they are called) and in the Green Beret pictorial section they show and describe the training as currently taught and as taught over 25 years since I attended SFQC.

The Groups bring in individuals to show their materials,(7th group is interviewing potential trainers as we speak),and the teams have members who do martial arts and most times it is done as part of the PT program.

The US Army program is the "Official" program but there are add ons to that training.

To add, I was sorely dissapointed with MAC when I got to my unit. I'm tempted to start risking a malingering charge on MAC days to get out of this waste of time. What we train is nothing more than glorified wrestling.