Costco gives you an extra 1 year beyond the Manufacturer's typical 1 Year warranty.
Many credit cards do as well, if you purchase with a credit card.
Square Trade is excellent.
Walmart offers Extended Warranties that have been solid as well, but Best Buy is probably a bit better as when they do trade ins, there is more selection.
Panasonic AX-200u / Optoma Graywolf 92" / Draper Luma 92"
Samsung 51F8500 Plasma / Vizio M422i LCD / Vizio GV42LF LCD / Vizio VP322 Plasma
Sony S790 BD / Panasonic BDT220 BD / Roku 2 XS & HD-XR / PlayStation 3
Oppo 983H Anchor Bay VRS / Denon 2930CI Silicon Optix Reon / Panasonic S97 Faroudja Genesis / Oppo 970HD Mediatek
Panasonic LX-900 Laserdisc / Aiwa MX100 Multi-region VCR / JVC S7600 S-VHS