There are multiple ways to share animation over the internet; animated .gif's, swf files (flash) and places like youtube and vimeo.
Here are some tips that might make it easier for people to critique your work:
1. Especially if it's rough animation, number your frames. A frame counter is a great, easy way to do this. Why is that important? Because it's much easier to discuss what drawing or group of drawings don't work and why when there is a way to reference them without confusion. "The drawing in frame 18...." and so on is going to be much clearer than "the drawing where the arm swings back.."
2. Use free sharing features like dropbox to upload .avi's or quicktime .mov if you want critique. Here's why: the ability to view an animated file on a frame by frame* basis by moving back and forth over the timeline as desired allows the person viewing the work to study WHY something about the animation may look strange. A viewer may look at a .swf and go "there's something strange about this around this point..." but a person looking at the same file who is able to look at it frame by frame may be able to say "hey, look at frame 16 - the spacing of the wrist gets really big here then suddenly gets small at 18, then big again at 20." or "in frame 48 the upper arm gets really really short." or "the drawing in frame 200 breaks the arc you've established, so it pops"
So putting up both a visible animation file AND access to a downloadable file should hopefully make it easier for people to critique your work; and that's what everyone wants, right?
*when I say look at something frame by frame, I mean having the file stopped and using the arrow keys to move foward and backwards through the file.
Here's something I would like to mention: for a downloadable file, you can take the individual frames of a flash animation, paste them in individual frames on the stage, put stop(); actions on all of the frames you need, and add back and next buttons with .swf based animation.
.MOVs are best for frame by frame reviewing. Also, .H264 compression is a good balance between weight/quality for such things too.
That said, I think VLC does an okay job to navigate frame by frame when viewing other formats but I haven't tried it in years.