Previously covered productivity app focus@will is an excellent way to increase productivity through listening. The web-based player contains a number of channels that play soothing music scientifically designed to help your brain focus on the task at hand.
ADD and ADHD sufferers, though, are usually left out in the cold when it comes to this kind of app. Since those with ADHD are simply wired differently, what soothes and enhances focus in the typical brain tends to have minimal—or even adverse—effects on those with ADD or ADHD.
Focusatwill tackled this problem by developing a channel specifically aimed at ADD and ADHD users. Instead of "soothing" tunes, the channel plays a "fast, very high energy, very intense genre of dark hardcore techno." That's the opposite of what most would consider soothing, but it seems to work for a subset of ADHD sufferers. Focusatwill has tested the channel with some of its in-house users, for whom it seems to work quite well.
I listened to the channel for a bit myself, and it's definitely not for me- but then, by design, it shouldn't be. This mom agrees that the sound is hard to take for non-sufferers, but her 9-year-old son, who suffers from ADHD, described the channel as the most conducive to focus, while the others tended to put him to sleep.
Like all other channels, there is an option to change the energy level to low or high from the default medium level. In all, the channel only has about two hours of material uploaded, but I'd expect that to change as they learn more about what works and what doesn't. Keep in mind that this is very much a beta experiment, so everything is subject to change, and quickly, but for now, I'd imagine this could be a huge deal for those for whom typical productiity apps just don't work.