There are approximately 1200 islands in the Adriatic Sea, 69 of which are inhabited.
A vast majority of the islands are located near the northeastern, Croatian coast. Here are the larger ones, sorted approximately from the northernmost to the southernmost ones, with a few notes in parens:
Aside from the above, there are three Tremiti islands just off the Italian city of Gargano, Perast islands in the Kotor bay, and St. Stefan, both in Montenegro.
All of the islands are tourist resorts these days.
There are two peninsulas, too, Istra and Pelješac.
For more information, see
http://islands.zesoi.fer.hr/
http://croatia.net/islands/
http://www.itwg.com/islands.asp
http://www.kornati.hr/
http://www.np-mljet.hr/
http://www.np-brijuni.hr/