I'd like to host a Google Gadget on our production app server which will provide a means of authentication and display some interesting information from our database.
Obviously I'd prefer to develop and test this outside of our production site.
Is there any means of testing testing a Gadget that is hosted on my dev box? I'm new to gadget development, but as I understand it they need accessible over the internet to run.
Gadgets do not have to be accessible over the public internet to run - just somewhere accessible by the server / page / portal that's trying to use them.
There are several ways you can test your Gadgets -
You can test it by deploying to your own iGoogle page rather than the production portal. Your gadget would have to be internet accessible in this case.
Several Java Portal servers can host Google Gadgets. (LifeRay, Sun Java System Portal Server, Weblogic Portal Server, JBoss Portal Server / GateIn, and many more.) You can run these locally on your development machine / network - so your gadget can just run locally.
Also, Apache has the Shindig project - an OpenSocial and Google Gadgets container - there are Java and PHP implementations available.