What is an excellent(easy to use) animation program?

[The_Doom-ed_one]

With the right knowledge, Flash is actually pretty good software and allows you to export a small variety of file types.

Adobe After Effects seems to have animation support as well, because I've seen some pretty high quality animations coming from people who used the CS (Creative Suite) series. I haven't used After Effects all that much, so I can't really tell you much else. Be warned, though, it's expensive.

If you want to go a cheaper route, you could always make a .gif image making each picture frame by frame and then using it in simple movie software. This process is a little more complicated and I would recommend using cell shaded characters with limited colors otherwise you'll get some nasty looking results with things like dithering and odd colors. On top of that, this technique is just plain cheap, and it shows, so I wouldn't recommend it if you are serious about animating.