You can have more than one connection string in the config file:
<connectionStrings>
<add name="Home" connectionString="Data Source=SERVER\SQLEXPRESS;AttachDbFilename=D:\data\MyStuff.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True"
providerName="System.Data.SqlClient" />
<add name="Office" connectionString="Data Source=FS-OFFICE\SQLSERVER;AttachDbFilename=H:\data\MyStuff.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True"
providerName="System.Data.SqlClient" />
</connectionStrings>
and access it something like:
SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["Home"].ConnectionString);
OR
SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["Office"].ConnectionString);
Hope this helps. :)