Magic Engine
Homepage of the best PC-Engine emulator.
It's not free but is worth its low cost considering its great emulation quality.
HuCards , SuperGrafx , CD-Roms , Arcade CD-Roms , everything is emulated !
Since version 1.0 Magic Engine uses Necstasy's database to identify CD games.

Mednafen
Homepage of the free and open sources multi-systems emulator developed by Sarah.
Available for Linux and Windows, Mednafen offers a very good HuCard and CD emulation.

Ootake
Homepage of the free and open sources PC-Engine emulator developed by Kitao Nakamura.
Available for Windows only, Ootake offers a very good HuCard and CD emulation.

Hu-Go!
Homepage of the free and open sources PC-Engine emulator developed by Zeograd.
Its emulation quality is average but Hu-Go! runs on several operating systems such as Windows , Dos , Linux , Debian , Beos , Solaris , etc...

PCEAdvance
Homepage of the free and open sources PC-Engine emulator developed by FluBBa.
This emulator runs on a GameBoy Advance system and does it pretty good.
CD-Rom emulation is partially implemented , but with restrictions !

PC-Engine Dev
Technical demos, hacks, translations can be found on Rich's homepage.

Sega Saturn, Sega Dreamcast, NEC PC Engine Hu Card, NEC PC Engine CD ROM, NEC PC Engine Super CD ROM, NEC PC Engine Arcade CD, NEC PC Engine Super Grafx, NEC PC Engine FX, Sony Playstation, Sony Playstation 2, Nintendo DS, Nintendo GameCube, Nintendo 64, GameBoy Advance, GameBoy Color, GameBoy, Super Famicom, SNK Neo Geo CD, SNK Neo Geo Pocket, XBox, Bandai Wonderswan games and consoles all in stock and ready to ship from this online shop.

Retrogaming, Resident evil / Biohazard, collectibles, figures, books and much more, more than 4000 items in stock.

Pcenginefx.com is the largest and one of the most well known sites related to the NEC line of video game consoles, and is the largest resource anywhere online where you can learn all there is to know about the NEC PC-FX.

PC-Engine Catalog Project is the online database dedicated to the PC-Engine and PC-FX games maintained by Bt Garner and Dave Shadoff.
It is by far the most complete on the web , all that is missing are the TOCs.

Flo's extremly complete and detailled homepage.
Everything you want to know about HuCards is here.

Laurent Kermel's new multi consoles website.
You can find many tests for HuCard and CD-Rom games.

Kabuki's homepage dedicated to the PC-Engine.
Mainly tests for HuCard and CD-Rom games here aswell.

Christopher Hawes' homepage dedicated to Turbo Grafx games manuals scans.