Don't you just love future tech? It's always fascinating to read about the new ways we'll be interacting with technology down the road. Just say the word "nanotechnology," and you've got my full attention. Or "robot." Or "flying car." (Actually, I think flying cars are a terrible idea, but that's a rant for another day.)While it's fun to imagine the possibilities, the truth is that for one reason or another, many of the great-sounding tech ideas we read about will never come to fruition. That's why we've put together a special feature showcasing five up-and-coming technologies you need to know about right now, not at some nebulous point in the future. Some of the technologies on our list are already in play; the rest will be by the end of this year. And they all have the potential to change the rules of enterprise and consumer computing.

As we compiled our hot list, a few promising technologies failed to make the cut:

Ultra-mobile PCs: The potential of Microsoft's ultra-ultra-portable Origami is interesting, but we've been suckered before by the promise of a fully functioning miniature PC. We'll suffocate if we hold our breath waiting for this category to bloom.

Flexible displays: We're sold on the inevitability (and desirability) of organic light-emitting diode (OLED) displays based on a flexible substrate that allows them to bend and fold. This is really cool stuff. But in terms of real-world use, we're still a few years off. We hope next year this technology will make our list.

WiMax: Last year's big story has turned into this year's big yawn. The promise of widespread neighborhood wireless networks sounds appealing, but carriers are finding it difficult to implement. Plus, why WiMax when Google will build you an urban wireless network for free?

So what technologies did make our list? Ajax, for one. It stands for Asynchronous JavaScript and XML, but Ajax is more about efficiency than anything else. Why click and wait for a whole Web page to reload when Ajax can deliver what you want on the same page? More and more, the Web is behaving with the speed and responsiveness of a desktop application, and we have Ajax developers to thank for that.

To find out the other four technologies on our hot list, read the story. Then I invite you to weigh in: What red-hot right-now technologies do you think we should have included? Please submit your suggestions--with URLs wherever possible--in the Comments area below.