Oh. Right. Silly me. That makes more sense.
Hmm. There are some other boards I visit which have rotating images... but that uses javascript, and the avatar image here has to be an image file rather than a pointer.
Unless... what would happen if you kept the same file name, but changed the image? The boards would update that, right?
So... you could tell the boards that your avatar should be ~/myavatar.jpg and then just change the image in that file.
You should be able to create a program that does that for you. Let's say you have 10 avatars that you want to use. Give each one a number (either in the program or by naming them avatar1.jpg, avatar2.jpg, etc). Then...
1. select a random number from 1 to 10.
2. delete myavatar.jpg
3. make a copy of the file that corresponds to the number chosen in step 1
4. name the copy myavatar.jpg
Shouldn't be too hard. Then, you can run the program whenever you feel like it, or find some way to automate it (have the program run periodically, or be called when myavatar.jpg has been accessed x number of times, or something like that).
Should work, right?
Paul