Ikura is salmon roe, those glistening orange globes you see on “gunkan,” the seaweed wrapped cylinders of rice topped with roe. If you’re buy salmon roe, look for sugiko, where the eggs are enclosed in the egg sac. They’ve been salted and/or brined in soy sauce. Applehome finds that the flavor is superior when the roe is purchased this way.
Other roe products that are worth investigating are Kazunoko (herring roe) and all forms of cod/pollock roe.
Uni is the roe of sea urchins. Some are put off by the texture of the tiny egg sacs; it’s soft and melts on the tongue. The best, and some say the only, way to experience uni is fresh from the spiny shell of the urchin. An experienced server will neatly open the shell to expose the roe. Try it on a slice of French bread.