Windows: If you're tired of managing five or six different live CDs for testing and troubleshooting, free program XBoot will help you merge them all onto one DVD or thumb drive, complete with a handy menu to choose between them.
I don't know about you, but I've amassed quite a few live CDs over the years that I'd like to keep, like GParted, Ophcrack, and the many flavours of Linux I have lying around. Unfortunately, they always seem to get buried under all the other CDs I have, or left at other people's houses. XBoot does away with the need for all that, creating one bootable USB drive with any ISOs you want on it.
XBoot has a simple drag-and-drop interface that lets you just throw any ISO you want into the list and burn them onto a DVD (or USB thumb drive). What's even cooler is that it has virtualization tool QEMU built-in, so you can test your drive and see what your menus will look like when you use it. It's a great app for anyone doing a lot of troubleshooting or other work requiring live, bootable media, so hit the link to check it out if you fall into that category.
XBoot is a free download for Windows only.