I would like to add a button under my theme manager which shows a thumbnail listing of available skins (that did not ship with the theme when it was installed).
I’d like to feed this listing from a file on a central server that I maintain.
Looking for some advice on how to best implement this within WordPress.
I will periodically add new skins to the available listing and would like for users of my theme to be able to view them and perhaps even see a “new” icon when a new skin is first launched.
I’m also interested in the merits of hosting and serving the file from Amazon s3 vs my own server
Your best bet here would be a specialized RSS feed set up on your server. You could bundle a dashboard widget with your theme that automatically pulls this RSS feed and displays the thumbnails and a description of the new skins that are listed on your site.
Step 1: RSS Feed
First, decide what information you want to display in the widget. I recommend a skin title, the thumbnail, a short description, and a link to further information.
Store this information as XML on your server.
Step 2: Dashboard Widget
Create a dashboard widget that routinely checks this feed and displays updated items on the dashboard. You can use just about any existing RSS reader widget as a model here… updates to your server-hosted XML file will automatically appear on remote WordPress dashboards in this section.
It may not have the visuals you described, but if you just want to show a basic text feed, the widgets already exists – on the default “WordPress Blog” or “other WordPress News” dashboard widgets, hover over the gray header bar and you’ll see a “configure” link on the right side appear. Click it and widget shows input fields for your RSS feed, title of the widget, how many items to show, etc.