Until very recently, my wife has worked for a small mortgage business
(about 5 employees) in Phoenix, Arizona.

A few weeks ago, her boss found out that she was of Mexican heritage
(she has light skin, and as such didn't get any negative attention). 
Yesterday at lunch, he unleashed a string of racial slurs towards
her... he also made it clear, in no uncertain terms, exactly what he
thought a Mexican was (suffice it to say he didn't think highly of
them).  There was an impartial witness to the conversation, so it
wouldn't be a simple he-said-she-said.

Not that it matters whatsoever, but she is as American as any of us...
she was born on an Army base, and is a fourth-or-fifth generation
American.

** I understand that any answer is not a substitute for legal advice :) **

Based upon readings and interpretations of Title VII of the Civil
Rights Act, it seems that since he is a small business owner (less
than 15 people), he is almost "immune" from any laws concerning racial
harassment.  We're waiting to hear back from the EEOC, but I was
wondering if there is any precedent or anything else to know about
this at all.

It would really, really suck for this to go completely unpunished.  He
is supposedly an Equal Housing Opportunity Lender, and it sucks for
such a blatant racist to have that designation.

As far as answer criteria:

1) Can he get away with it completely unscathed?
2) If the EEOC is unable to help, where should we look to for some solid help 
   on the matter?
3) Any support networks of folks who have gone through the same thing?

Thanks very much..

Are you sure that it is not you that is trying to build a case ?

If your wife is of fourth or fifth generation American then her family
has probably been American for longer than some of the boss's
ancestors.

'Until very recently' and 'Yesterday at lunch' do not add up
- was she sacked yesterday PM or today AM ?

It is extremely likely that her boss dislikes first generation
immigrants, it is also extremely likely that he regards her as 'one of
the lads'.

Chances are, that if he blew off steam in front of her and an
'impartial' witness, that he took them both out to lunch, with the
'witness' as a duenna, and he fancies your wife something rotton.

Chances are, also, that your wife is winding you up.
Girls normally only say what they want to let on.

A slight miscalculation, as it sent you to the computer, rather than
earnestly enquiring whether the Mexican Indians have their own version
of the Karma Sutra.