Astroclock HTML5 Canvas Applet
This applet uses geolocation to get latitude and longitude data for astronomical calculations; if you select "Not Now" on Firefox, or otherwise dismiss a browser pop-up without making a selection, it will start after a few seconds timeout has elapsed, just as if there were a network outage while looking for the location data. The location can be altered at any time with the slider controls.
Planetary positions, moon phases, etc. have not been rigorously tested away from roughly zero longitude; but at least BST gives me some confidence in timezones. Check with the "Your Sky" map to confirm. There are tooltips for the planets, to help identify which speck is which.