Scavenger Needed!!!

shrimp....crap....lobster

All of which might be eaten. See if you can find a butterfly pulcher. Cool colors, neat shape, huge eyes--though prone to hiding. Loaches would be the other option.
 
I'd have to agree with Orion Girl on this one, Most Crustaceans will end up being food for Oscars, if they azre big enough to defend themselves, they usually rip up fins trying to catch the fish for food. Loaches would be my reccomend, if you don't like cats. remember there are a lot of really cool cats out there, So if you haven't looked around you may find something you like.
 
I know you said you aren't interested in catfish.....but you should take a look at the lace cat. They are very interesting to watch and do a GREAT job at cleaning up oscar mess. I couldn't be more pleased with mine. The are lightning quick and dart around like a shark in a feeding frenzy during feeding time. They are also "pleasing to the eye" in my opinion.

Here's pic if you haven't seen one (yes....I've posted it a hundred times now. :D :D) : http://www.roadrashed.com/Aquarium pics/PICT0023.JPG
 
AquariaCentral.com