You can be a consultant on anything as long as you have the right expertise for the topic. One example is a consultant who helps business-school students with applicants. Famous ones charge each applicant $3,000 per business school. Basically, what they do is help students with their résumé, essays, and interviews.
You can also coach people over the phone and the Internet. An example of coaching can be a career as a life coach, in which you advise and guide people to achieve personal goals. According to LifeCoach.com, individual clients can be charged from $200 to $1,000 per month while corporate coaching will net life coaches about $1,000 to $10,000 every month.
You can coach people on pretty much any type of topic, from dating to personal finance.