A friend of mine went in for a minor nose operation after a punch up
and something went wrong in the operation. He has been in a coma for 3
weeks with a blood clot in the middle of his brain. Does alternative
medicine have anything to offer here?

Dear Declan, 

There are many who claim to have "cures" for coma and I must recommend
that you'll see a doctor/alternative healer before using one of the
solutions offered here. I must also state, that I am not a medical
professional (neither alternative nor conventional), just interested
in alternative medicine and pscyhological related methods of healing.

The Ayurvedic Alternative Medicine suggests the usage of the Vacha
herb to assist coma patients. You can read more about it in this site
- http://www.ayurveda-herbs.com/15a.htm Other recommended herbs are
Brahmi,   Hing (asfetida) and Karpur (comphor) (see
http://www.aarogya.com/Alternative/ayurveda/herbs.asp)

Prayers to your friend.

On medline and google found references to 

physostigmine
http://www.kfshrc.edu.sa/annals/173/96-294.html

flumazenil
http://www.biopsychiatry.com/flumazenil.htm

hyperbaric therapy
http://www.strokedoctor.com/hbo16.htm

They will probably use a "clot buster" 
Neurosurgery  2002 Feb;50(2):421-4; discussion 424-5 
Use of intraventricular tissue plasminogen activator and Guglielmi
detachable
coiling for the acute treatment of casted ventricles from cerebral
aneurysm
hemorrhage: two technical case reports.  Azmi-Ghadimi H, Heary RF,
Farkas JE, Hunt CD.

Department of Neurosurgery, University of Medicine and Dentistry of
New Jersey,
New Jersey Medical School, Newark, New Jersey 07103-2425, USA.

Somewhere down the line as bioelectromagnetics develops a device 
may be available along the lines as reported in this paper:

Bioelectromagnetics  1997;18(5):341-8  
Bioelectric potential gradients may initiate cell cycling: ELF and
zeta
potential gradients may mimic this effect.  Beech JA.


From Merck Manual:

Coman Treatment is nonspecific and consists of preventing systemic
diseases, such as pneumonia, and of providing good nutrition,
effective nursing care to prevent pressure ulcers of the back and
limbs, and physical therapy to prevent contractures of the
extremities. Unconscious persons cannot perceive pain. Those who show
evidence of regaining awareness by responding consistently to
questions or other specific stimuli must be managed carefully to avoid
inflicting any more discomfort than they already experience.