I actually spend lots of time at Blu-ray.com, and I don't even own a Blu-ray player yet.
That probably sounds silly, but my first purchase of one is probably not that far off (with new formats and technologies, I typically like to wait for a couple generations of players to cycle through before diving in).
I do tons of research in advance of such an investment, and of course that means the media too.
I really like the reviews of Blu-ray discs on this site...after all, it's the top-of-the-line format out there right now, with the high def craze that's going on and everyone upgrading their equipment.
I go here to review music discs, and have found every review I've read so far to be really helpful. They get into a high degree of technical jargon without losing you, and focus on both the video and audio portions.
This site is also a cataloger of sorts, helpfully indicating what's actually available out there in the Blu-ray format. Since we're less than 2 years removed from the format war with HD DVD, it's going to take time to get through older movies and videos...I'm guessing part of it will involve how high the demand is...otherwise there doesn't seem to be any rhyme or reason to it.
For example, The Band The Last Waltz from 1978 has been out on Blu-ray for over a year now, but none of the Star Wars movies are available, so forget logic.
In the case of my personal amusement; when I went there and couldn't find Pink Floyd Pulse on Blu-ray (a concert from 1994 that I wasn't expecting to find on the format, but I thought I'd check anyway), I was treated to a review of David Gilmour Remember that Night instead, and found it had some features and extras that are more appealing to me anyway, such as ancient Floyd bits. There was another excellent review of Rush Snakes & Arrows Live at the site.
I'm scoping all this stuff out in anticipation of picking up a few titles to augment the collection.
It's not just music, there's reviews of movies as well...and anything else, for that matter, that's out on our most recent and illustrious media format, Blu-ray.