Apple's new OS X 10.4 Tiger has a feature called Dashboard. Dashboard runs little widgets which are a combination of HTML, Javascript, CSS, and sometimes specialized plugins. I've found that some of them, which don't require a plugin, can often be run from the browser.

The widgets live in :Library:Widgets and are really specialized folders. Right click (control-click) a widget and choose Show Package Contents to look inside. Typically there's a single .html file, which when clicked will open up in Safari.

I've made a little html page with links to a few that work. Apple, being security minded, doesn't let you run a file on your local computer when clicking a link on a non-local webpage. To try this out control-click this link tiggers and choose Download Linked File. Double click the tigger.html file on your Desktop and it will open in Safari and the links should work.

Of course, if you don't know and/or trust me you should verify the file's source or not run it. Don't run any ol' thing you get off of the net... ":^)

Just a quick experiment. Other Dashboard items might work, all depends on if they require a special plugin or not. Simple ones and web based ones seem to work best.

UPDATE: well, hey, how about that! Someone already created an app where widgets can live in the wild: Widget Amnesty.