Is it possible to have a Per-Tab Work Offline extension? That is to say, you'd right click on a specific tab, have an option to choose Work Offline *just for that tab*, and from then on the contents of that tab would not be able to communicate with any servers until you reset the setting.

This would be neat for a number of very useful cases, especially for MegaVideo.

A browser-wide Work Offline setting would also be good alongside the above.