The first night of RH has become, along with Pesach and Tu B’Shvat, a seder. I’ve heard people here talk about the Rosh Hashana Seder. It's a real cultural phenomenon, even if you don't hold like the Hagahot Asheri (that Phoebus showed me) that one dips the heap of a sheep in honey (eeeewwwwww!)
I was thinking (out-of-the-box) that it’s almost the diametric opposite of the Pesach seder. For example, on RH we eat the head of a fish, and on Pesach we eat karpass. UPDATE #2: Also, on RH we eat sweet foods, and on Pesach we eat bitter foods.
UPDATE: If you, like me, can't stand the idea of eating fish heads, you may want to try this - after all, it's simana milta, a symbolic thing:
You can even chop off their little jelly heads!!