No product is complete without a top-ten list of cool features, so here's mine for Popfly.

1. It's easy to get. All you really need is Firefox 2 or IE 6 or 7. Oh, and Silverlight, but that's pretty easy to get.
2. It's easy to use. People have talked about wanting programming to be like connecting Lego blocks; Popfly gets pretty close.
3. You can create mashups with it. This is kind of its purpose, but it's neat nonetheless.
4. You can create web pages with it. We "borrowed" the Office Live team's page editor technology.
5. You can use it with Visual Studio. If you're a VS user, you can get Popfly Explorer and start to share projects with your friends on Popfly.
6. You can use it with Windows Live Spaces. There are a few tricks to it that we'll document shortly, but you can both pull stuff from Spaces and embed Popfly creations into Spaces.
7. You can create Windows Vista Sidebar Gadgets. Again, a few tricks to it, but neato.
8. You can use it with your own blog. We'll just hand you the iframe and you can embed it.
9. You can extend it with new blocks. Don't like our blocks? Add your own.
10. It has some attitude. We had fun creating it. I hope it shows.