NESten was done in Delphi, so were a lot of other emluators like DPCE (a PC-Engine emulator), check out the link below for a quick emulator/language listing:

http://www.multiplayer.it/itaprogami...u_sorgenti.asp

P.S. I love the idea of a Delphi based emulation site. Especially if it will include examples and simple tutorials to get people started working on new emulation projects.