I feel like adding a few more I use.
Open Broadcaster Software - Should be obvious, really. It can stream and record videos to YouTube, Twitch, Hitbox and more. It's free and easy to use, and even easy on the computer. Available for Windows, with a different version for other systems.
CDBurnerXP -
Already mentioned. It's a good and easy to use CD/DVD/BD burning tool. It has a bunch of features Nero has too. Windows only. Although people also recommend
ImgBurn, I think that it would only be useful for people who want a ton of options on CD burning. I don't like ImgBurn for some reason, I think it has a very weird design.
MagicDisc - Talking about tools with weird UIs, here's MagicISO! It works very well for a simple program. Never had any issues with it so far (I had a ton of issues with Nero before, where XP would simply stop working because of the thing) and the simple, taskbar-only interface makes it kind of neat too. Windows only.
EDIT: I forgot to talk about what it does. Go me!

Basically, it can mount ISO files in virtual CD/DVD drives.
Midori Web Browser - If you ever need a lightweight browser for any reason, this is the one. It has a occasional glitch here or there, but it's extremely easy on the CPU (besides, it's still in beta much like OBS). It can support a great amount of HTML5 and CSS3, can support Flash and has a bunch of features popular browsers have. It's available for Windows
and Linux.
Tagaini Jisho - A good tool for learning Japanese, although I only use it for basic "translations", a friend who is learning Japanese told me that it helps him a lot. Thanks to this software I was able to play Densha de GO!, so I think it works very well. Available for Windows, OS X and Linux.
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♫"If you're still young, still young, still young
Tomorrow you'll be old, you'll be old, you'll be old!
Unless your heart, your heart resists
Youth is something that never dies!"♫
Thanks to Rambly, who let me borrow one of their old post layouts.