An anonymous reader writes: Whenever I install a fresh operating system on my computer, I immediately grab a handful of programs that I simply must have. After that, I generally wait and install other pieces of software as I need them. My list of known, useful programs has dwindled over the past few years as projects died, ownership transferred, and functionality changed. At the same time, I've begun to have use for certain types of software that I've never needed before. So, I'm curious: what pieces of software do you find the most useful and reliable? Don't feel the need to limit yourself by operating system, platform, or hardware. If you're so inclined, a brief description about what makes the software great would be helpful, too.