Is this what you are looking for:
From MSDN:
maxconnections
The default two-connection limit for connecting to a Web resource can be
controlled via a configuration element called connectionManagement. The
connectionManagement setting allows you to add the names of sites where you
want a connection limit that is different than the default. The following
can be added to a typical Web.config file to increase the default value for
all servers you are connecting, to a connection limit of 40.
<configuration>
<system.net>
<connectionManagement>
<add address="*" maxconnection="40" />
</connectionManagement>
</system.net>
<system.web>
...It should be noted that there is never a limit to the number of
connections to your local machine, so if you are connecting to localhost,
this setting has no effect
or is it this:
http://blogs.msdn.com/darrenj/archive/2005/03/07/386655.aspx