Mac: Cloud storage services such as Dropbox and Google Drive make it easy to continue what you're working on no matter where you go -- but you do have to actually remember to sync the right files. Quicksand automatically syncs your most recently opened files, so you always have them on hand -- even if you forget.
Quicksand lives in your menu bar and regularly checks your most recently used files, syncing them to a folder on your computer. You can tell it how many files to sync, tell it which folders or file types to ignore (so it doesn't sync private or very large files), and you can choose where it syncs those files -- whether that's Dropbox, iCloud Drive or somewhere else.
It's a very simple idea that works really well, as long as you set it up right. Check out the video above to see it in action (the useful part starts at 2:35), or download it at the link below to try it out for yourself.