Web application Popfly takes a building block approach to mashup creation, allowing regular folks like us to connect services like Flickr, Twitter, and maps to your heart's content and your creativity's limit. It's all available through a drag and drop interface somewhere along the lines of Yahoo Pipes. Popfly is free to use, requires a Windows Live login and the Silverlight browser plugin. It's currently in beta, and be aware that I saw significant slow-down on my computer when using Popfly. Hot mashups currently on the site include Flickr Mappings and Seattle Traffic via Virtual Earth, but the real question is: Does anyone want to build their own mashups? If you give it a try, let's hear your thoughts in the comments.