I know you said 50" plus, but you might want to check out Westinghouse brand LCDs. They are absolutely amazing value for money. The top of the line is currently a 47" LCD panel, but they are rumored to be adding a 56" some time this year. I just picked one up and it's great - plenty bright enough even in a daylit room, good anti-glare coating on it. And best of all it's 1080P, which if you're using a PC or Mac to drive it means you get a really crisp and clear picture at a reasonable resolution!

They're relatively cheap too. Westinghouse is trying to establish itself and make a name in the consumer electronics market so they are consistently selling way under their competition. You might want to check out the AVS Forum on the topic. If you like what you see, you can pick it up from Crutchfield (30 day satisfaction guarantee and free shipping included) for $2499.