ZXGP32 is a ZX Spectrum emulator coded by David Douglas. It emulates the 48K and 128KSpectrum. Details:

CPU: 95%, almost all of the documented op-code are emulated but there are just so many undocumented ones to get around to!Keyboard: Nicked the idea from Frodo to have a pop-up keyboard. Ability to assign the ‘B’ button to a certain key. Can toggle CAPS and Symbol Shift.Joystick: Control Pad and Button ‘A’ emulates Kempston input.Display: Full colour screen, including emulation of both ‘Bright’ and ‘Flash’.Sound: Experimental, I would NOT suggest turning it on as it is not pretty and tend to bum out after a while!File Types Supported: SNA, Z80, TAP

http://www.gp32emu.com/