In addition to the ARM platform, it is now possible to emulate a MIPS (big endian) or MIPSEL (little endian) machine running Debian under QEMU. It could be used as a cheap MIPS/MIPSEL development machine to test your packages, provided that you have a not to slow i386, AMD64 or PowerPC computer.
Running on an Athlon 64 X2 3800+ the emulated system is around 10% faster than my SGI Indy R4400SC 200MHz and possibly with much more RAM (my emulated system has 512 MB of RAM). Also for the ones who know about the Indy SCSI controller, the transfer rate is around 13 MB/s on the emulated system.
Note 1: I have written this howto very quickly, so there are probably some mistakes. Comments are welcome.
Note 2: I have updated the ARM howto to take in account improvements from Debian-Installer RC1