Legal anime streaming site Crunchyroll have started to stream their material in 1080p. As of writing this it seems that not all of the series are available in 1080p, but are still available in 720p which had been available for a while. I would personally assume that they will be changing this soon and show all of their shows in full 1080p glory.
The most popular series' of the site, such as Bleach and Naruto, are available to be streamed in 1080p now, but this appears to only be available to premium members. You can get a 14 day trial of this before signing up.
I admit that I used to only use 'fansub' streams for my anime previously, but after seeing the difference in quality I don't see me ever going back to them, and this new change will keep me there even longer!