Get an account on YouTube, be funny, become a partner, get thousands of dollars of ad revenue. 😀
Apparently YouTube "celebrities" like Fred and supermac18 are making a killing doing what they do.
As for how I saved up for my Macs, the most recent ones have been from tax refunds and good old fashioned saving. Put away $100 a month into a savings account and force yourself not to touch it. In a year's time, you've got a MacBook or an iMac.
The first one I bought, my PowerBook G4, was an Apple financing deal that I should not have taken given my financial situation at the time. Long story short I ended up oweing a LOT of money on credit at something like 28% interest, and it took years to pay it off. I don't even WANT to know how many hundreds (thousands?!) of dollars in interest I threw away on that PowerBook. Don't make that mistake!
It gets easier after the first one because you can resell the old one to recoup some of the cost of a new one.