You can also take them to a dry cleaner. However, take them ONLY to a dry cleaner who has the sign from Ugg stating they are certified in Ugg cleaning.
On another note, I had to take my daughter to the orthopedist for a dance injury. She was wearing the Uggs I got her for Christmas. He said those are the absolute WORST things you can wear on your feet. He calls them "winter flip flops". He showed me how you can bend the foot part and twist it, etc with no resistance whatsoever. He said they have no support at all and no one should be wearing them unless it's for a very short walk --- definitely not meant to wear all day or when doing a lot of walking. He said he has tons of patients who have major foot/leg problems from wearing them.
You know, I had never really wanted her to get the Uggs. I always found them to be hideous-looking and never believed they had support for the foot. Well, I saw the ones I got her (the Sunburst Uggs) and they were on sale ($225) and I knew she wanted them for Christmas so I bought them. Now, I wish I hadn't.