• Authy App - Two-factor auth for Android and Desktop... syncs your auth stuff across devices so you don't have one point of failure. I don't like the companion extension, I just use the app.
• PushBullet - Notification sync between Android and Desktop. Quick Reply to SMS and IMs from desktop. Push links from one device to another.
• Google Keep - There is also a purely web version available so an app isn't totally necessary but i find it useful as a synced todo list between my Android and desktop.
• HTTP Switchboard - Like NoScript (plus partial AdBlock) for Firefox, but a bit cleaner, and it starts out with a good whitelist. microBlock is an alternative based off of this project that simplifies things if HTTP Switchboard is too complex.
• HTTPS Everywhere - Use HTTPS whenever it's available.
• iChrome New Tab - Styled roughly like the now-dead iGoogle, it brings a bunch of services together on your new tab page. I can see my e-mail and RSS feed new items in one spot, which is nice.
• Reddit Enhancement Suite - If you use Reddit this is a must.
• Enhanced Steam - If you use Steam this is a must.
• Chrome Remote Desktop - Access your desktop from another device. Punches through firewalls and routers automatically.

As for bandwidth, what I don't get is how do you get your files back if you can't guarantee the people you rented disk space from actually have their machines turned on?

Easy, do it the same way RAID does it: redundancy.