But say you take Twitter as an example. If someone had told me back in 1995 that I could send 130-character text messages to all my friends over the web, I'd have said "So?". Now I've got a bunch of friends nagging me, "Are you on Twitter yet?" (I'm not, but I do get nagged about it fairly often.)

Technology doesn't just change what's possible, it changes what people want. The reason there's demand for something like Twitter is because now everyone is online, nearly 24/7, and so the value of an online service that tells you what your friends are doing has gone up significantly.

You may be right - actually, from a numbers perspective, you probably are. But if I had a few million to invest and the chance to blow $15K on something like AwesomeHighlighter, I'd think there was enough of a possibility of success to make it worthwhile. People are reading more online, and their reading is much more participatory. That's a different environment than in 99/00.