I haven't tried sea urchin yet - so I guess I need to add that to the list. I like the caviar too, especially the little red ones, salmon roe, I think, also.
Some other suggestions for people who don't want to try the raw items the first time out, in addition to California rolls, are eel, tempura rolls, and softshell crab rolls. The eel is a bit exotic, but comes with a sweet tamarind(?) sauce. The tempura is basically fried shrimp (beware tails) and vegetables in a light batter. And softshell crabs are yummy most any way you get them.