EMULATORS
ZEsarUX
Emulates all Sinclari machines and some more, like Jupiter Ace or Amstrad CPC 464.
ZX Spin
The best free alternative to Spectaculator.
FUSE
Working 16K, 48K, 128K, +2, +2A, +3, +3e, SE, TC2048, TC2068, Pentagon 128 and Scorpion ZS 256 emulation, running at true Speccy speed on any computer you're likely to try it on.
zxsp
Macintosh emulator (Mac OS X and older versions).
ASp
Accurate speed, great sound. It supports .tzx. It hasn't +3 support yet.
Bacteria
Its basic characteristics is so large reduced it is, about 4Kb. The main objective is to occupy the minimum space of hard disk possible and to offer a totally trustworthy emulation in speed, graphs and sound.
ZXSpectr
It's a ZX Spectrum emulator written entirely in Assembler. It runs under MS-DOS and it's the only one that emulates the Inves Spectrum + (a Spanish clone)
vbSpec
Another ZX emulator for windows.
INFORMATION
Don't you know what it is an emulator? It's simple: an emulator is a program that let you run games and programs of your old computers into the modern PCs, Macs, mobile phones and new generation consoles. You could load the images of those games, whose are available for thousands in Internet.