Is there anything inside of my 51" Rear Projection tv that would come in handy? thanks guys.

It depends on what you're wanting to do with it. If you're wanting to create an Lumenlab style rear-projection TV, like SPK did, then sure, you could salvage the cabinet itself and the fresnel screen at least.

If you're wanting to make a typical front-projection LCD projector, then no, there would be nothing of use to you.

I think there'll probably be a large front surface mirror in it. I've also heard that there could be a hot mirror in it (near the bulb).

I would imagine there will be wires in there, and maybe some brackets or something that could come in handy...

If you take it apart slightly and post some pics we might be able to see some parts that could be useful...