There's also the old-fashioned way of accepting money from people – through the mail.  You could have people send checks, money orders, or even cash.  I'd discourage the last one.  Even if you make sure the person conceals it well and offer no guarantees, it's still bound to cause unpleasantries if it doesn't arrive.

With a personal check, the money isn't really yours until it "clears" at the bank and is deposited into your account.  If you are rendering services and accepting checks, make sure you wait for it to clear first.  Money orders are a little safer and can be deposited pretty much like cash. 

Be clear about which currencies you’re dealing with here.  The internet means an international audience, but often a US-centric one.  As a camgirl from Canada who occasionally accepted money orders as payment for membership, I had to be very clear about which kind of money order had to be sent – Canadian banks will not cash the green “postal money orders” that most Americans are used to using, it must be a special international money order.

If you’re accepting mail, you also want a safe address to publish, such as a PO box.  Check the safety and privacy section of this site for information on keeping yourself secure when accepting anything by mail.