TestDrive is an Ubuntu application that is especially designed for non-technical users to easily download and run the latest Ubuntu development daily snapshot in a virtual machine. More here

TestDrive can download: Ubuntu Desktop, Ubuntu Server, Ubuntu Alternate, Ubuntu DVD, Ubuntu Netbook Edition or other ISO for which you’ll have to enter the URL. For now it downloads and runs Ubuntu Lucid, but the URL is automatically updated so when Lucid comes out, TestDrive will download and run Lucid+1.