You've heard me say "all you need is a good idea" a few times here 'n there.
Here's a list of vehicles from which passive income can flow, which start with, and are mainly comprised of, a good idea.
Also, I've linked to many books, tapes, dvds, cds, and other informational materials on their associated subjects. Just pick one, they're all very lucrative, its simply a question of finding your passion, your vehicle, and taking action!
Single Audio Cassettes, CDs etc
Mentoring & Apprenticeship Programs
Speaking Internationally or via web conference
Speaking in breakout sessions
Speaking representing your employer or company
Corporate training programs
Boot camps of any subject
Tele-boot camps or web based
How could you best encourage a blogger to blog?