What's the diff between www.mediamier.org
and http://multimedia.lycos.com/ ?

You ever tried a do a search in
http://multimedia.lycos.com/ for say
dragonball cels ?

Sure multimedia is offering a direct download
link which is not good but  it looks like
http://multimedia.lycos.com/ actually stores
the thumbnail in their database.

I seem to remember 4 or 5 years back
yahoo did something like this too, and I bet
you there a MANY other big sites out
there doing this. 

Also remember these *are* servers indexing 
your site, so contact them and ask them if
there is some way to stop their servers from
indexing your site. e.g norobots.txt file or
maybe they have a some other way stop it
with a meta tag.

Just ask them with out getting angry :)

And remember YOU must protect you images
If you don't want them to be stolen or linked to,
Then LEARN to stop it youself or do out them
on the web in the first place.