Take a class online about a cultural phenomenon or why not a a course about regional food or that popular science you find interesting.
Try geocaching in your area. Geocaching is a sort of treasure hunt game where you need a GPS-enabled device such as your mobile phone. You can find several geocaching sites that provide you with tasks and a real adventure where you are to find the hidden cache.
Take a group exercise from the comfort of your home. Fitness and group fitness has found its way online and you can find cardio as well as yoga classes, to name few.
Play tourist in your hometown, find out what attracts tourists to where you live, and try to learn about the sights and activities. This has the bonus that you will have more to talk about when you greet friends and acquiantances when they come to visit you.
Find more inspiration!
Check out virtual tours and exhibitions online. If you want to go biking and explore the nature around your hometown, as well as be on the road for a day or two, then bikepacking might just be for you.