Load Balancing and Backup

I assume this issue has been solved repeatedly, but I cannot find any 
information on it...

I have a website that runs reports on data from a postgres database.  An 
average report takes about 10 minutes.  I'd like to load balance it so I 
can have multiple people run reports without causing the login request 
to take forever.  Also, it is rather important that data updated in the 
database be updated on all mirrors of it immediately - not with an 
hourly or daily update.

What I would most desire is a program that pretends to be a postgres 
server.  I can log into it with psql, a jdbc driver, or php's 
pg_connect.  When I do a select (no update) command, it will send that 
off to the least loaded mirror.  When I do an update/insert/delete, it 
hits all the mirrors.  Also, it can designate one database (most likely 
local to this pretend server) as the master so I can easily clone it to 
make more mirrors.

Does anything remotely similar to that exist?

-Chris