Tussen Kunst & Quarantaine is an Instagram account with pictures from old masters, re-enacted by people. There's an amazing amount of reenactments on the account already, in varying degrees of accuracy, and of course you can add your own if you feel like it. In any case it's worth a look, some of the reenactments are hilarious!
TechSmith is offering video tools for free, to support those of us suddenly faced with new challenges in our home office or self-isolation. This includes a screencast tool (in case you need to show someone else how to use a programme, for example).
On Jools Wilson's site, you can find a lot of things to colour in or cut out and make, among them a Neolithic house, or a Hug in a Box - which is beyond cute, and might cheer someone up if you send it to them (assembled, of course).
If you can read German and like to go outside into the mountains, or climb, or boulder, here's some hints from German DAV (alpine sports association) on how to keep fit and active without going out.
And finally, XKCD has a comic about the virus - from a different perspective: