[perlgeek]

The key is to provide value to the reader or consumer.

Blog posts can be valuable (by educating or entertaining, for example), but writing valuable blog posts is a lot of effort.

Side projects can be valuable, but creating valuable side projects is effort.

So I guess it depends on what you're good at. A side project is usually something you're passionate about, so it's a good starting point. But if you like writing, blogging is still the way to go.