You must be familiar with Session Manager, an extension which allows saving of current sessions to be opened for later use. TabCloud is a Firefox and Chrome extension that not only saves sessions, but also allows synchronizing them with your Android phone with its Android app. To use this extension, a Google account is required. On one end this might appear to be a setback for people who do not have a Google account, however, this is meant to ensures security of the saved data and its synchronization.
After installing the TabCloud extension for Firefox or Chrome, you can login with your Google account and access it from the TabCloud icon next to the Address Bar. Clicking on this icon allows saving the current session (floppy icon), deleting a saved session (red minus icon) and opening a stored session (by clicking on the name of the saved session). When saving sessions, users are given the choice to add a name for easy identification. The saved sessions also have favicons, which makes it easy for the user to identify what websites are saved in a particular. The developers have ensured that other than the current Android app, they will also be providing sync support for iPhone in near future.