There is an app called Groove Maker 2 that is free today: I recently saw someone post it to the app directory, but I can't find it. Anyway, it's free.
I have intended to bring up this subject, and when the entry for Groovemaker 2 was posted, I was going to discuss
this but got busy, then forgot. The person who submitted the app said it was totally inaccessible and not worth getting, and I strongly disagree. It's certainly not the coolest app, and it's certainly not the most accessible, but inaccessible? Definitely not. I often get apps people say are inaccessible, and surprise surprise, a about a quarter of the time I get an app it's at least usable. Maybe not accessible, maybe not obviously accessible, but if we are going to judge the accessibility of an app, I think that two or more people should look at an app before judging it inaccessible. In the case of Groove Maker 2, the buttons could be labeled better, it's true, and if you hadn't spent a few hours with it you might not realize that those buttons simply mark the positions on the grid. What you do is double tap and hold on one of them, then move your finger around and listen as the beat changes. You can figure out a change pattern you like, record it, then add effects. The only inaccessible part of that is the x-y pad used for applying them. Therefore the rating needs to be updated in a huge way, but I can't even find the entry now. It should be in music, but I've even done a general search and still can't find it. Anyway, the app is free today. When you get it, restore purchases. Once you hit restore purchases, the app will say you successfuly restored them and you'll have a lot of beats to work with. I used to use this app quite extensively, but I found the free version of the game far too limited. With the full version for free, who knows what I'll find now.