Through the TA forums, we heard about Klungkung temple (which is also called Kerta Gosa) in Klung Kung. We visited on our way from Ubud to Candi Dasa and it was one of my favorite places. I found the paintings on the ceilings depicting the karmic results of various (mostly bad) actions fascinating. There are many lovely statues throughout the gardens and along the walls. We enjoyed the little museum in the grounds with many old photos with interesting information about the area and its history. The buildings served as court where the local priests would cast judgement over local disputes and the like. The main building sits in the middle of a large pond, or small lake, with lots of lily pads, making it a beautiful scene.
Also, don't be tricked into buying a sarong outside. There are a few pushy sellers near the entrance that wait for cars carrying tourists to pull up to try to make a sale. As soon as you walk through the main gates, you can borrow one from the attendants who will even help you tie it on. If you're in the area, do make the stop.