A closed for business or down for maintenance switch and sign for your Community

I was wondering what you folks do when you upgrade your respective Dolphin-based communities. Other communities, when they go down for maintenance have this professional message/webpage that notifies users/members that the site is down for whatever reason. Good example of one:

http://themeforest.net/item/vinta-ss-under-construction-page/full_screen_preview/54270?clickthrough_id=19746859&redirect_back=true&ref=PauliusR

It would be a nice idea for Dolphin; integrated with future Dolphin versions (or as a mod provided its easy to install and the instructions are clear AND the developer is willing to disclosure compatibility with future versions) controllable via Administration Panel. For non-licensed versions, the page would branded (Boonex could put what it wants there). However, for licensees, the page would be flexible in that licensees would be able to change the message (e.g., under construction, down for maintenance, etc.). For high-quality mod, I believe that this could fetch a good price because its unique.

Also, the mod or the integrated technology would allow for the site owner/developer to work on the site without having to take down the entire site. It would also kick in automatically should the site go down because of site-related issues (versus server related issues).