Hey I don't know if this has been asked already or not but here goes:
How do you have animation in avatars/signatures?
Or just Photoshop Imageready

You can also use Flash if you'd like, but I recommend photoshop.
its just a row of boxes, each box edit the pic, add on too it, make it change
etc.
and then upload it as a single image?
wtf.... ok heres what you do to make a good animation its simple. first you create a layer for each slide that you want. you can do this in photoshop or whatever. then you switch to image ready. you open up the animation window then there should be a little button with a triangle. you click on that then there will be an option to "create slides from layers" click on that and you got as many layers as slides. then you just click on the time thing at the bottom part of each slide for animation. dont forget to save it as a GIF file.
What if I wanted to take a short clip from a movie (like 2 seconds long), I have seen that on other websites
well it would be a big file size if you did it in gif even if the file was compressed. i would advise you do it in flash.