I'd personally not waste my money on a PogoPlug. I've been able to do this for years now already, and anyone can pretty easily. Most Windows versions already have IIS web server built in, or can easily be installed, and then it's pretty simple to setup file downloads via the web, with or without password protected logins. And you just share the folders that you want to be able to download stuff from. Here's an example on how to do that: Clicky

That's not as "pretty" or elegant as PogoPlug, but it does the same thing, minus the RSS feeds that most people probably won't use, but as always, there are software authors out there who make up for it with freeware. It's pretty easy to install PHP or ASP.NET on your IIS server, which opens your computer's abilities up to all kinds of cool, pretty stuff. There are tons of free PHP scripts out there to share your files over the web with password protection, like:

CloudOsys

Or PHPFileNavigator, which is Open Source, meaning free, and PHP developers all over the world contribute to identifying and stomping out bugs, making it better and more secure all the time. Here's a page of screenshots of it, and here's a demo of it in action so you can try it out for yourself before installing it.

There are of course, also ways to do it with Linux servers too, and other Windows programs specifically desigend for this exact type of thing, both pay programs and free ones, like iRemotePC.

iRemotePC is just one of countless programs like this. A quick Google search for IIS or PHP File Sharing will start ya off on finding the right one for you. PogoPlug is made for people who don't really want to take a few minutes getting thier hands dirty by installing and configuring their own computer with all of the free stuff already out there, and truth be told, it's not really very hard at all. PogoPlug is basically just a site who hosts software like PHPFileNavigator (and sells people a gadget) instead of people Hosting it themselves, and then it just points to your computer for the files. With something like the above options, you'd just be cutting out the middleman and doing it yourself.