I also tried gluing business reply card "postage paid" things to my envelopes. But that never worked.
....
I read a text file once that suggested coating the face of your stamp with Elmers glue.
I managed to get the business reply thing to work a couple of times, but it's mostly useless because it has to be sent from the town that is listed on its permit. Could be good if you're trying to get back at a local organization, but not exactly the best for sending letters to friends
I think the elmer's glue thing is a lot of work for not a lot of return. Maybe if you got one of those $2 stamps and just re-used it over and over again with friends who would peel off the gunk -- scratch that, still a bad idea. I think that even forgery would be slighty less of a pain in the ass (still wouldn't save you anything though).
I've sent things that had a different from address than the town I was in (because I was travelling), maybe that usps worker was just really gung ho or something, or maybe they were just a dick. Once I tried to send a package that had insuficient postage (I didn't know) and they somehow managed to get my work number! That was freaky and really embarrassing hehe.