Great List. I would add "Host an intern". Not all internships have to be paid (though you'll get a better applicant pool). And many jobs can be done virtually.
10 Ways to be an Awesome Alma Mater AlumDecember 1, 2010 in alumni, college, guest, Top10
This one is personal and probably niche, but if you've ever played a sport, consider coaching. At my alma mater, Fairfield University, I started the men's club volleyball team as a student. However, being an 18 year old player/coach was daunting and trying to do both made me mediocre at both. Once I graduated, I coached both the men's and newly formed women's club volleyball teams for a tiny stipend (covers gas $$). The players got to focus on playing and getting better while I handled all the "business" aspects of sports, including choosing who plays and who sits, which can cause major riffs between friends if a player is forced to coach as well. Coaching a team also gives them more credibility when they travel - administration is more likely to let them go on a weekend trip to a tournament if their is an adult present to keep people in line. Parents also greatly appreciated my help. If sports isn't your thing, there are plenty of other types of clubs looking for leadership and mentors. If you're unemployed and looking to keep your skills sharp, volunteer to work with the marketing club, or accounting club, or math club, etc. Finally, if you consider yourself to be a subject-matter expert, offer your speaking services. It could be for a specific school (business, liberal arts, etc) or just for the career planning department.