Poor Man's Patent:
What is a "Poor Man's Patent"? As an ehow.com article describes it, "a poor man's patent is simply, just a postcard you send through the United [States] Postal Service. Just print a copy of the product you designed on it. Address the postcard to your self [sic]. Once it comes back stamped by the postal service it is a 'Poor Man's Patent.'" The article takes it one step further, suggesting that a "better way to get a patent is to go to Lulu.com. Download a picture of your product. Then make a calendar, T-shirt, coffee mug whatever they offer. You design what [it] is you want and printed on it copyrighted by your name and date. You pay for it. Then Lulu.com sends your design on the product you chose, this is a legitimate patent plus it is copyrighted and no one else can steal it." Do not under any circumstances attempt to "patent" something this way. It doesn't work. The Chicago Tribune nailed it in a 1985 article: a "poor man's patent [is a] term most appropriate in the sense that the inventor who relies on such protection is virtually assured of remaining a poor man."
(1) Can I legally prevent somebody from doing what I invented?
(2) Can I keep doing what I'm doing?
(3) Can I stop somebody else from getting a patent on what I'm doing?
While some materials, like the ehow article referenced above, are clearly and obviously wrong in some material ways, even well researched materials -- even recent court cases -- can become wrong or misleading very quickly. Any reference materials more than a few months old should be assumed invalid as to at least some points. The law is changing that rapidly (a big case came down last week from the Federal Circuit on a 6/5 vote about whether delay in enforcing rights waives patent damages). The speed of change is such that relying on anything other than a lawyer (or, if you can't afford one, at least careful reading of current USPTO materials) is likely to lead to mistakes.
One advantage of Fresno I've found as an inventor is that there is at least one excellent patent lawyer (the one I use), and I suspect there are others. Moving my patent work from two large LA law firms to her in Fresno has resulted in large cost savings (Fresno is simply a better priced legal market) and there has been no compromise on the quality of the work.