OnLive Desktop originally went live back at CES earlier this year, and since then it's been making magic happen on iOS devices everywhere, whether you've used it yet or not. The cloud-based service provides a Windows computer packed with standard software, streamed right to your iOS device, practically whenever and wherever you need it.
Seriously, if you have not tried OnLive yet, it is just as amazing as we've said it is. The gaming side of things will allow you to play all sorts of PC games on your Mac, and while the gaming app hasn't yet been released on the App Store, the Desktop app is out and working right now. Go sign up on OnLive's site and use it for completely free to see for yourself.
Back when the Desktop service was first announced, OnLive also promised that a subscription service was coming, and now it's here as well: OnLive Desktop Plus is available on OnLive's website as well. For the cost of $4.99 a month, you get priority access to the service, a cloud storage option (so you can actually save your files out on the server), the option to attach files to webmail services (so you can send them back to any computer you like through email) and a full installation of Adobe Flash to play with.
This also means that Flash is installed on the Windows computer, so you can pull up a browser on the cloud server's Windows setup, pull up a Flash-based website, and browse Flash over the web, right on your iPad. There have obviously been solutions for this before, but this is as easy as it gets.
As you can probably tell, I'm a huge fan of the service -- there is still a little bit of lag occasionally (and I unfortunately haven't had a lot of luck using the service over a bad Wi-Fi connection, which really limits the possibilities while traveling, I'm sorry to say), but otherwise it's very impressive to see, and it really opens up what you can do with your iPad in terms of playing PC games and using Windows software. If you haven't given OnLive a shot yet, definitely try it out for free and see what you've been missing.