The power of software expressions to manipulate other expressions is one of the reasons software is so useful, but it causes confusion as well. There is a whole variety of ways that an expression can take other expressions and manipulate them, beyond the standard copying to a new destination.
Framing & Context Shifting
One simple way of manipulating other expressions that doesn't even include what most people would consider "programming" is the one called "framing". Framing is when you create a website that splits the browser's screen into two or more pieces. One piece shows some website with presumably useful information, the other shows other content, typically ad banners or other money-making material, that has nothing to do with the useful site. The issue of whether this is legal or acceptable has come up several times in court, but (unfortunately) they all ended up settling out-of-court.
As early as 1997, TotalNEWS.com linked to hundreds of news sites on the web and showed them in a frame, surrounded by TotalNEWS.com's sidebar, and showing TotalNEWS.com's URL (because that's how frames work). An out-of-court agreement allowed TotalNEWS.com to continue linking, but to stop framing. In 1998, a dental website, Applied Anagramic Inc, framed content from another dental website, Futuredontics Inc. The court decision that resulted was ambiguous, saying:
... the Court finds that the cases cited by the parties do not conclusively determine whether Defendants' frame page constitutes a derivative work.
Neither case manages to provide any guidelines beyond "Framing might be bad." Despite the amount of time this issue has been with us, court cases have only given loose guidelines against deceptive framing, with little clear definition on what deceptive framing is. The solution to this problem was that the problem simply went away. Convenient, but doesn't leave us with much precedent.
The essence of framing is shifting the context of an expression. One example of this is the McSpotlight site protesting against McDonald's. In their own words:
McSpotlight hijacks McDonald's new site (using Frames) and deconstructs its carefully worded PR spiel.
Emphasis mine. Compare the context surrounding McDonald's web site to the context of the McSpotlight's tour. The entire purpose of McSpotlight's tour is to change the context with which you view McDonald's page, and thus change the message sent to the viewer. Unfortunately for the purposes of this essay, McDonald's web site has changed and the only part of the tour that works now is the home page and a couple of other isolated links, but you can get the gist.
Despite the legal ambiguity, several sites continue to frame content, even large ones like Ask.com and About.com.
Content-Blind Manipulation
While framing has attracted significant attention, it is by far the least technically sophisticated example of content manipulation I can think of. It does not actually affect the original content. If we take one step up on the complexity ladder, we find content-blind replacement scripts. These programs situate themselves between the receiver and the transmitter, intercept the message, and perform some of replacement on the words, paying no attention to the actual content of the page. For instance, you can see a Swedish Chef-ified version of my home page.
I call such manipulation techniques "content-blind" because they are not really looking at the content of the web page. Regardless of the contents of the web page, some manipulations will be performed on whatever is available. No matter what web page you run these scripts on, the results will be essentially the same.
One of the most interesting variations on this theme is the Shredder. The Shredder is an artistic statement about the nature of the web, which ties in rather nicely with the points I'm trying to make in this essay. From about shredder:
The web is not a publication. Web sites are not paper. Yet the current thinking of web design is that of the magazine, newspaper, book, or catalog. Visually, aesthetically, legally, the web is treated as a physical page upon which text and images are written.
Have a look at iRi through the Shredder. What's really interesting about Shredder is that it is itself an artistic expression, absolutely independent of the web pages it may produce as a result of use. The Potatoland.org website appears to contain many other expressions of a similar nature.
While behind each of these scripts lies some static source code, upon which somebody holds the copyright, the static source code does not reflect the true nature of the program/expressions. When you look at the iRi through Shredder, where does iRi end and Shredder begin? The only way to understand Shredder is in its relation to other expressions, which has no equivalent in the static expression world. Considered on its own, Shredder is meaningless; only when acting on something does it have any existence as an expression.
Content-sensitive manipulation
On the highest end of the complexity scale, there are programs that can take some content and dynamically alter it to some specification. Some censorware attempts to work this way, by "bleeping out" profanity and blocking pornography. Another example is translation programs like Babelfish that attempt to translate web content from one language to another. These can be very complex and the only limit to what they can do is human imagination and technical skill. What does that mean about the ownership and liability of the expression that comes out of such manipulation? Is there any legal difference between this and content-blind manipulation or framing? These are not easy questions to answer.