1, files)
Many (all?) of the alternatives mentioned for direct file transfers (sshfs, sftp, scp (was rsync ❤️ mentioned?)) relies on having SSH access to the remote PC. This works great if you’re the owner of both machines and they’re both regulars on the network, but if not—say, it’s your room/flat/house mate or you’re having friends over or you’re at a LAN party or LUG meetup—it may not be practical (or secure!) to create login shells for whomever you want to receive files from/send files to. I think this is what Teleport aims to be for.

2, links)
If you use Firefox and you have Firefox Sync set up, you can both right‐click links and "send to" another Firefox instance and you can also do the same with open tabs (by right-clicking on the tab). It is glorious and I use it frequently to send links between laptop and desktop and phone!