Flexemu - An open source EurocomII/V7 emulator for Linux and Windows.
Free42 - Open source HP-42S emulator for Linux/i386, Mac OS, PalmOS, Pocket PC, Windows, and Zaurus X/Qt.
FunnyMu - A freeware Creativision, Funvision, and Whizzard emulator for Linux/SDL.
GXemul - An open source MIPS machine emulator for Linux.
HiRISC Simulator - A freeware emulator for Windows of a system designed specifically for the Applied Systems Programming course at the University of Akron.
James the Animal Tamer's Emulators - Freeware APF, Aquarius, Exidy Sorcerer, Interact Family Computer, MC-10, NEC PC-6001A, Panasonic Personal Computer, and TRS-80 emulators for Windows.
Japanese Computer Emulation Centre - A site dedicated to the emulation of Japanese Machines including X68000, PC6001, PC88, PC98, MSX 1/2/R, Sharp MZ, Sharp X1, Fujitsu FM7, and Fujitsu FM Towns.
KCemu - An open source emulator of the KC85 homecomputer series for Linux and Windows.
mic1 - A Java-based simulator which implements the Mic-1 microarchitecture described in Chapter 4 of Andrew S. Tanenbaum, Structured Computer Organization, Fourth Edition. [Open source, GPL]
PearPC - An open source PowerPC emulator for Unix and Windows.
Project8080 - Covers the development of a Heathkit H8 emulator on Macintosh.
SIMH - An open source collection of emulators for Windows of historical computers, including GRI-909, HP 2116/2100/21MX, IBM 1401/1620/1130/System 3, PDP-1/4/7-11/15/VAX. Also provides software kits, system photographs, and technical papers.
Solace - An open source Sol-20 emulator for Windows.
SPRINT - A freeware Sprinter emulator for Linux/i386 and Windows.