While personal projects are good, even more impressive is contributing features and/or bug fixes to larger open source projects.
It's sometimes much more challenging to dive into an existing project, learn their frameworks/style/design, and work with existing contributors.
However it's also much closer to what happens on a real development team. Whereas a project with a single author can show coding skill, working in a large open source project shows collaboration, communication, and soft skills as well.
It is a huge gold star on a resume in my opinion.