This is something that I actually run into a lot at customer sites. They have a lot of friction during development between different connection strings that developers use during development. For example, we may have one developer using:
<add name="RavenDB" connectionString="Url=http://localhost:8080" />
While another is using:
<add name="RavenDB" connectionString="Url=http://localhost:8191;Database=TheApp" />
This usually causes a hell of a lot of trouble in most teams (or maybe you have developers that use SQL Express, and some who installed SQL Development, etc).
That is friction, and you want to deal with that as soon as possible. The easiest thing to do is actually:
<add name="Ayende-PC" connectionString="Url=http://localhost:8080" /> <add name="Ayende-Laptop" connectionString="Url=http://localhost:8191;Database=TheApp" />
This works, because the connection string name is now the machine name (System.Environment.MachineName). That is a great first step, because it means that you can get things done without fighting over the connection string in the web.config.
Another alternative is to have a default connection string, and allow to “override” it with the specification of a connection string specific for the machine.
It is a small thing, but it actually helps quite a lot. You can extend this to other settings as well. For apps that have a lot of settings, I usually take them out of the Web.config into a Default.config file, and the configuration reader is set to look for [MachineName].config first, and only then at the Default.config file.