When it comes to fandom and especially character shrines, there is precious little in the way of actual websites these days. I've cobbled together a few remaining websites, as well as some archived ones thanks to DNT's Milieva. There's links to relevant blogs, forums, and communities as well, since that seems to be where fandom has migrated.
Cephiro - First and foremost, this is the place to go if you want to have fun with other MKR fans. Established in 2006 and just relaunched in 2012 after a hiatus, this place is fun, laid-back, and full of people who adore MKR.
Definitely Not Tokyo - In the spirit of the old major MKR info sites such as Fuu's Cephiro and Primera's MKR Page, Milieva is on a mission to build up a new and modern MKR information site.
In My Heart - A music and general information website. A longstanding classic.
fuckyeahrayearth.tumblr.com - A Rayearth-themed spam tumblr, sorted with tags.
If you wish to link back to this website with a graphic, you can use any of the following. It's not 1999 anymore so I really shouldn't have to say this, but upload them to your own server, please.