The Samsung Galaxy Mega officially straddles the line between "big but usable" and self-parody with your choice of a huge 5.8-inch screen or a 6.3-inch behemoth.
They also offer powerful dual-core processors, fast HSPA networking with LTE support on the 6.3 model, 8 or 16GB of internal storage, a microSD slot, Wi-Fi, Bluetooth, GPS, NFC, 8-megapixel rear cameras, and 1.9 megapixel front cams.