That's a pretty good answer.
But, yes, for several years a claim such as:
1. A method of operating a web site, comprising the steps of:
(a) presenting via a browser a graphical display area;
(b) dividing the visual display area into discrete regions; and
(c) collecting payments from advertisers to permit their material to be shown in allocated discrete regions.
...would be fine "subject matter" for a patent under 35 U.S.C. 101.
The next hurdle is novelty under 35 U.S.C. 102 which in general requires that you were the first to invent the subject matter, and that it has not been published or in public use for more than one year prior to the date of the patent application.
Then, the next hurdle is obviousness under 35 U.S.C. 103. The general idea is that the difference between your claimed invention and something that was around before your invention should not be "obvious" to one having ordinary skill in the art to which the invention pertains. What this typically means is that if I claim to have invented something that combines several things, it is okay if those things were around individually for a long time. But if those things, combined with some known suggestion, motivation or teaching to combine them, was around for a long time, then the invention may be "obvious" even if there is no specific record of them actually having been combined before.
Finally, the patent application must provide a concise written description of the invention in sufficient detail to demonstrate that it could be reduced to practice by one of ordinary skill in the pertinent art without undue experimentation, and the description must set forth the preferred manner you conceive of carrying out the invention.
That, and a good chunk of money, are all you need.
One of the best books on the subject for the non-patent-attorney is "Patent It Yourself" by Jon Pressman, published by Nolo Press.
