This article is from the Apple ][ Emulator Resources Guide, by Alex Maddison with numerous contributions by others.
There are a growing number of emulator pages specifically or tangentially related to the Apple II computers.
Jonathan Badger's Apple II Home Page http://geta.life.uiuc.edu/~badger/apple2.html
Chi-Yuan Lin's Apple II Page http://www.tfrin.gov.tw/D-FI/~cylin/apple2.html
Chris's list of emulators for the PC (including the Apple II) http://members.aol.com/chrissalo/emu1.htm
Chris, Mark & Terry's Apple II Home Page http://www.duke-net.com/apple/main.shtml
Emulation.Net - John Stiles's list of emulators for MacOS - Apple II Page http://emulation.net/apple2/index.html
Marat Fayzullin's [FMS] list of emulators - Apple II and Macintosh Page http://www.komkon.org/fms/comp/sys/Apple.html#apple2
Arthur Levesque's Apple II Page http://www.erols.com/backslash/apple2.html
The Pirate's Guild - Dave Morrison's Apple II software download page http://www.ozemail.com.au/~deth2/a2/