archive, exerpt, and thumbnails

hi,
is there a way to have the exerpt automatically displaying the thumbnail of an image posted.
or is it only feasable by hand, by handwriting, manually
probably am i not clear
the quesiton is how to have an archive page with thumbnails
first answer is : use the exerpt
ok
but, is there a way to “automate” this ?
well, again, thanks a lot