It's true, VZW charges a monthly fee to tether, via cable or WiFi.
1. You can root and tether for free.
2. You can buy a tethering app from the app store, without root access, and pay a one time fee for the app.
3. You can pay VZW the monthly fee and tether.
Keep in mind that tethering without a plan is against your Terms Of Service with VZW.
Having said that I don't know anyone who's been caught tethering and charged by VZW. It can happen and they can cancel your service.
I used to tether using an app I got called Tether, on my Blackberry. It worked great and I didn't use it much, about 2GB a month.
http://market.android.com/details?id=tether.android