My 430EX II that my folks got me for my birthday just came. Whenever I get something new my cats are the first to help me test it out.
Obviously much much better than the built in flash and I think it really made the details of her fur pop.
Chloe by
Seminolez, on Flickr
And here's a 100% crop of her eye. You can actually see the reflection of me laying on the ground taking the photo: