Mapping sites to other sites without using FastCGI/DB

[Brian Kirkbride]

Hello,

I'm new to Nginx but have been very impressed with it -- thanks for 
contributing this great software.

I have a mass virtual hosting setup, all sites have the same config 
and will be served with server_name * (wildcard).  The config is very 
simple, just serving some static files.  I want to keep the Nginx 
boxes as simple and light as possible -- no FastCGI, no database.

Some domains will simply be an alias to another domain.  I know that 
for one or two domains, you could simply do a rewrite from 
ALIASDOMAIN.com/(.*) to REALDOMAIN/$1, but our situation is more 
dynamic and we can't update the config file all the time.

Is there as way to have:

docroot/
   realdomain.com/
     [content]
   aliasdomain.com/
     aliased_to

where aliased_to is a text file containing the real domain?

Or what about:

docroot/
   realdomain.com/
     [content]
   aliasdomain.com/
     aliasto_realdomain.com

Something like that?

In apache mod_rewrite I would do this using maps, but my Nginx skills 
are weak!

Thanks in advance,
Brian Kirkbride