Ok, forgive the title, but sometimes things can be really surprising. I asked a question today on the Model-Glue list about the XML file used to configure MG apps.
One of the things I had noticed while editing my config file was that I had to repeat my application name multiple times. I asked if there was someway we could abstract that. Turns out - XML has something already built in - XML Entities. Wayne Graham sent a very nice solution in to the list and has blogged about it here.
Even if you do not use MG, I highly recommend reading his blog entry.