We just returned from our Orlando trip today

We visited SeaWorld on 12/29/08. Here is a list of prices for "extras", listed on the map;
Xtreme Zone (Mega trampoline) $8
Paddle boats $4
Sky Tower $3
Food for the stingrays was $3
It costs $7/person to feed the dolphins. I asked if I could go in to help my daughters feed the dolphins, but not buy a tray of food for myself to feed the dolphins. They said "no"; everyone who goes into the feeding area is charged $7. It was totally worth the cost (in fact we wound up doing this twice!). Just be prepared for the cost, especially with a large family. They do take credit cards there, so you don't need cash.
Hope this helps!
Have a great time!