One of the goals of our department is to keep our alumni involved. Most importantly this relates to staying in contact with people. Not only is it a good idea to check in with former professors but it is a good idea for alumni to check in on current student to offer pointers, advice, or opportunities for students to know about what they are doing.
Here are some ideas of things you could do for current students:
Answer an email from a current student
Send in info on how your program helped you
Advice for the program on what it can add or change to benefit its students
Come to campus to talk about what you do
Join a video conference
Offer a day, week, or summer when a student could come an observe you at work
Offer internships (both for credit and paid)
Take part in mock interviews to help students prep to find jobs
Here are some ideas of how to hook up with other alumns: