Certainly the Internet has been a fantastic boon for people like me who like to plan their own independent holidays. I spend quite a lot of time researching future trips as I imagine lots of people do.
I find that if you decide on when and where you want to go, it's not too hard. However, there's a huge gap in the market for something that helps you decide just where and when to go. Anything that attempts it usually lacks any credibility because they're just a channel for massive tour packages. It's an information rich domain that's crying out for a solution but it also needs the right business model to support it.
Similiarly, airfare websites also assume you have decided when and where you want to go. What I really want to know is what fabulous seat sales and hotel deals are available over a particular stretch of time and then I need help deciding whether any of those places would be worth going to. Even better, I want to tell a website my idea of a good holiday and have it go and find the best deals that match it.
I recently discovered the TravelJungle meta search engine which looks a step in the right direction. It aggregates other aire fare sites and delegates bookings to them. It's a start but has a long ways to go.