As someone who has done plenty of candidate screenings, an active Github account is a big plus. I get to see how you interact with others, I get to see your code style, how you approach version control, how you deal with bug reports and feedback, and I can get a sense of your programming prowess in a context that isn't cooked up for some interview.

Accounts that are just vimfiles and the skeleton of a never-again-touched project are boring. Forked repos are neat, because they show what you're interested in and what you've been exposed to. Forked repos that you've contributed to are even better. Your own projects that others have filed issues and pull requests on is the motherlode; that tells me a ton about how you do the job I'm hiring for.