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.
http://www.jcec.co.uk/

Evenson Consulting Services' SWTPc 6800/6809 Emulator
Windows 9x/NT GUI emulation of SWTPc 6800 and 6809 systems. A Simulated Machine Environment (SME) emulation plus .dsk file downloads.
http://www.evenson-consulting.com/

GXemul
An open source MIPS machine emulator for Linux.
http://gavare.se/gxemul/

st20emu
A freeware ST20 emulator for DOS.
http://sourceforge.net/projects/st20emu/

TinyELF
A freeware emulator of CDP1802 based microcomputers for Mac OS X.
http://www.tinyelf.com/

Flexemu
An open source EurocomII/V7 emulator for Linux and Windows.
http://geocities.com/flexemu/

KCemu
An open source emulator of the KC85 homecomputer series for Linux and Windows.
http://kcemu.sourceforge.net/

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]
http://www.ontko.com/mic1/

Project8080
Covers the development of a Heathkit H8 emulator on Macintosh.
http://members.aol.com/heath8080a/

The Susie V pages
A freeware BCL Susie V emulator for Linux/i386.
http://www.geocities.com/susievem/SusieV.html