Shortly after I learned about the amazing paint application, Colors! DS, two more DS homebrew applications came to my attention that are even cooler!
Animanatee is a simple, easy to use animation program (not to be confused with this guy) that allows you to export your scenes into .avi files. It has a very intuitive interface and once I loaded it up I was animating right away without needing to read any instructions. It supports 1 BG layer and 1 animation layer. It also has limited onion skinning, which only shows a ghost of the previous frame. You can't zoom in to draw at higher resolutions so it gets tough to make consistent drawings and inbetweens, but for very simple things it's ok. Here's a quick bouncing-ball test that I made using Animanatee:
Flickbook is another pencil-testing software for the DS and I think it's been around longer and has more users. I needed to read the instructions before I could make sense of the UI, but it does have some features that are more advanced than those in Animanatee. It has onion skinning for three frames in either direction, the ability to zoom when you draw, and the ability to cut/paste. I suppose I could deal with the clunky interface if I really wanted the extra features, but the deal breaker for me was when the application froze on me, but told me not to turn off my DS. I looked up the problem online and some people said that turning off the DS after a freeze caused them to loose data on their memory card. I'm not going to risk all my game saves because of a buggy application. I turned mine off with no ill effects, but I'd rather just stick to Animanatee. I'll support the underdog with the fantastic usability, and hope that the features get updated.
UPDATE: There is, in fact, a slightly newer version of Flickbook (0.2.1) with some small updates that make a big difference. The interface is WAY better looking and the buttons are more recognizable for the functions they perform. Also added was the ability to flip through your drawings with the d-pad just like in Animanatee which makes it just feel SO much more natural. It didn't crash on me either. It's getting tough to decide which app I like better.
There is a third animation application for the DS that has my attention, but it is being developed for retail so it isn't a homebrew application. It's called Inchworm and it has VERY impressive drawing tools. It has a lot of the basic features found in Photoshop and Illustrator along with some basic animation tools. It looks like it will make it a lot easier to create full colour animation on the handheld, but it's animation tools are not any better than the existing homebrew applications.
Even with their limitations these applications have gotten me excited again about animating traditionally. I can't work up the effort to get my pegboard out of storage, punch paper, scan all the pages, and compile it. I also don't have a tablet to be able to use some of the great PC applications. But I DO have a DS and I likes me some homebrew animation apps! There are better ways to animate, but having a pencil tester in your pocket makes it easy to get a quick animation workout while you're on the plane, waiting for a bus, or sitting through a bad Hayden Christensen movie.