What are you trying to keep up with?

If it's research, then, like with any field, read recently published papers. Some organizations, like IEEE, also put out publications that summarize recently published research.

If it's in-demand skills and programming languages, just scan through job postings.

If you want to keep your programming skills sharp, then I suggest joining an open-source project. Just be up-front about what you can contribute if you go that route.

Just curious: what did you do before?