I'm pretty sure you can't patent an algorithm at all right now. That is to say, you can't call your invention an "algorithm." That's why you'll see everything called "system and method."

I would still say no to all software patents, sorry. The purpose of a patent is to make public the information so that others can learn from it, but so they can't copy and market it (without your consent/license). If your algorithm is a trade secret, then you won't want it to be listed at the USPTO. Someone would have to reverse engineer your software to figure it out. And in that case you still have recourse against someone ripping off your implementation.

Patents should all be specific. Something too broad should automatically fail the basic test for patentability. But many don't. Many law suits are file by companies achieving the same result but with different methods. That's not patent infringement, but good luck arguing that with a company that has deep pockets and nothing to loose by spending years in court.

I hate the order system at Amazon, patented or not. It's cumbersome and I don't know why it's not called "100-Click Ordering."