all u can eat sushi
Lighthouse off of 3rd Street in Santa Monica has all you can eat sushi and sashimi (at night). Dinner is just under $20 and lunch is cheaper. It's much better than Todai, and I think the food is pretty good. Of course, it's not as good as a good sushi bar, but one of the best sushi buffets I've had, especially for the price. I have had tori there, which is pretty good for a sushi buffet.
Todai Restaurant (chain) on wilshire and one in the beverly center and elsewhere;
Midori (Ventura Blvd) - all you can eat in an hour;
Somewhere on the corner of 2nd Street and Arizona in Santa Monica - the lighthouse or something.
Remember - though - all you can eat sushi is never all that satisfying.