website-less participation
Inspired by James' Reading as participation in the indie web.
Encountering websites or even the idea of them are great starts toward making one. Stronger incentives include not only enjoying their designs, but also reading text, viewing images, or listening to media embedded within. These activities don't require having made a website. Neither does the more involved step of getting in touch with webmasters by comments, guestbooks, email, social media, or any other contact method. Any or all of what I mentioned can be considered valid and essential forms of community participation.
That said, I'd like to expand more on James' point of sharing what you find. Informing a writer that you took the time to read what they wrote, if not remix or repurpose it, can be gratifying for both parties. You don't have to stop there though. You can share their websites or anyone else's with so many other people too, whether physically or digitally. With how much more difficult distribution can be compared to creation, do what you can to make it easier for your favorite works to circulate.
An aside: If an idea that you shared circulates within a community, but you never actually get to encountering said community, are you part of that community?