Son 2 giorni che cerco di realizzare questo:

ITestService:
<ServiceContract()>
Public Interface ITestService

<OperationContract()>
<WebGet(UriTemplate:="/{value}")>
Function Pappagallo(ByVal value As String) As String

End Interface

TestService:
Public Class TestService
Implements ITestService

Public Sub New()
End Sub

Public Function Pappagallo(ByVal value As String) As String Implements ITestService.Pappagallo
Return value
End Function

End Class

WebConfig: (l'ultimo che ho provato..)
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<system.serviceModel>
<services>
<service name="WcfService1.TestService">
<endpoint
address="http://localhost/TestService"
binding="webHttpBinding"
contract="WcfService1.ITestService"
behaviorConfiguration="webby"/>
</service>
</services>

<behaviors>
<endpointBehaviors>
<behavior name="webby">
<webHttp/>
</behavior>
</endpointBehaviors>
</behaviors>

</system.serviceModel>
</configuration>

Vorrei solo fare una cosa del genere:

http://localhost:2800/(qualcosa)/Pappagallo/ciao

e che nel browser ritornasse: ciao

ci credete che non ci sono ancora riuscito?